The I-d diagram of humid air was developed by a Russian scientist, Professor L.K. Ramzin in 1918. In the West, an analogue of the I-d diagram is the Mollier diagram or psychrometric diagram. The I-d diagram is used in calculations of air conditioning, ventilation and heating systems and allows you to quickly determine all air exchange parameters in a room.
The I-d diagram of moist air graphically connects all the parameters that determine the thermal and moisture state of the air: enthalpy, moisture content, temperature, relative humidity, partial pressure of water vapor. Using a diagram allows you to clearly display the ventilation process, avoiding complex calculations using formulas.
Basic properties of moist air
Surrounding us atmospheric air is a mixture of dry air and water vapor. This mixture is called moist air. Humid air is assessed according to the following basic parameters:
- Dry bulb air temperature tc, °C - characterizes the degree of its heating;
- Air temperature according to a wet thermometer tm, °C - the temperature to which the air must be cooled so that it becomes saturated while maintaining the initial enthalpy of the air;
- Air dew point temperature tp, °C - the temperature to which unsaturated air must be cooled so that it becomes saturated while maintaining a constant moisture content;
- Air moisture content d, g/kg is the amount of water vapor in g (or kg) per 1 kg of dry part of moist air;
- Relative air humidity j, % – characterizes the degree of air saturation with water vapor. This is the ratio of the mass of water vapor contained in the air to its maximum possible mass in the air under the same conditions, that is, temperature and pressure, and expressed as a percentage;
- The saturated state of humid air is a state in which the air is saturated with water vapor to the limit, for it j = 100%;
- Absolute air humidity e, kg/m 3 is the amount of water vapor in g contained in 1 m 3 of humid air. Numerically, absolute air humidity is equal to the density of moist air;
- Specific enthalpy of moist air I, kJ/kg – the amount of heat required to heat from 0 °C to a given temperature such an amount of moist air, the dry part of which has a mass of 1 kg. The enthalpy of moist air consists of the enthalpy of its dry part and the enthalpy of water vapor;
- Specific heat moist air s, kJ/(kg.K) – heat that must be expended per kilogram of moist air to increase its temperature by one degree Kelvin;
- Partial pressure of water vapor Рп, Pa – the pressure under which water vapor is found in humid air;
- The total barometric pressure Pb, Pa is equal to the sum of the partial pressures of water vapor and dry air (according to Dalton’s law).
Description of I-D diagram
The ordinate axis of the diagram shows the values of enthalpy I, kJ/kg of the dry part of the air; the abscissa axis, directed at an angle of 135° to the I axis, shows the values of the moisture content d, g/kg of the dry part of the air. The diagram field is divided by lines of constant values of enthalpy I = const and moisture content d = const. It also contains lines of constant temperature values t = const, which are not parallel to each other: the higher the temperature of the moist air, the more its isotherms deviate upward. In addition to the lines of constant values of I, d, t, lines of constant values of relative air humidity φ = const are plotted on the diagram field. At the bottom of the I-d diagram there is a curve that has an independent ordinate axis. It connects the moisture content d, g/kg, with the water vapor pressure Рп, kPa. The ordinate axis of this graph is the scale of the partial pressure of water vapor Pp. The entire field of the diagram is divided by the line j = 100% into two parts. Above this line is an area of unsaturated moist air. Line j = 100% corresponds to the state of air saturated with water vapor. Below is an area of supersaturated air (fog area). Each point on the I-d diagram corresponds to a certain heat and humidity state. The line on the I-d diagram corresponds to the process of heat and humidity air treatment. General form I-d diagrams of humid air are presented below in the attachment PDF file Suitable for printing in A3 and A4 formats.
Construction of air treatment processes in air conditioning and ventilation systems on the I-d diagram.
Air heating, cooling and mixing processes
On the I-d diagram of moist air, the processes of heating and cooling of air are depicted by rays along the d-const line (Fig. 2).
Rice. 2. Processes of dry heating and cooling of air on the I-d diagram:
- B_1, B_2, – dry heating;
- B_1, B_3 – dry cooling;
- В_1, В_4, В_5 – cooling with air dehumidification.
The processes of dry heating and dry cooling of air are carried out in practice using heat exchangers (air heaters, air heaters, air coolers).
If the humid air in the heat exchanger is cooled below the dew point, then the cooling process is accompanied by the precipitation of condensation from the air on the surface of the heat exchanger, and the cooling of the air is accompanied by drying.
I-d diagram for beginners (ID diagram of the state of humid air for dummies) March 15th, 2013
Original taken from Mrcynognathus in I-d diagram for beginners (ID diagram of the state of humid air for dummies)
Good day, dear beginning colleagues!
At the very beginning of my professional journey, I came across this diagram. At first glance, it may seem scary, but if you understand the main principles by which it works, you can fall in love with it: D. In everyday life it is called an i-d diagram.
In this article, I will try to simply (on fingers) explain the main points, so that you can then, starting from the foundation obtained, independently delve into this web of air characteristics.
This is roughly what it looks like in textbooks. It's getting kind of creepy.
I will remove all the unnecessary things that I will not need for my explanation and present the i-d diagram in this form:
(to enlarge the picture, click and then click on it again)
It’s still not entirely clear what it is. Let's break it down into 4 elements:
The first element is moisture content (D or d). But before I start talking about air humidity in general, I would like to agree on something with you.
Let's agree “on the shore” on one concept right away. Let's get rid of one stereotype that is firmly ingrained in us (at least in me) about what steam is. Since childhood, they pointed me to a boiling pan or kettle and said, pointing a finger at the “smoke” pouring out of the vessel: “Look!” This is steam.” But like many people who are friends with physics, we must understand that “Water vapor is a gaseous state water. Doesn't have colors, taste and smell.” These are just H2O molecules in a gaseous state that are not visible. And what we see coming out of the kettle is a mixture of water in a gaseous state (steam) and “water droplets in a borderline state between liquid and gas,” or rather, we see the latter. As a result, we get that in this moment, around each of us there is dry air (a mixture of oxygen, nitrogen...) and steam (H2O).
So, moisture content tells us how much of this vapor is present in the air. On most i-d diagrams, this value is measured in [g/kg], i.e. how many grams of steam (H2O in gaseous state) are in one kilogram of air (1 cubic meter of air in your apartment weighs about 1.2 kilograms). In your apartment, for comfortable conditions, 1 kilogram of air should contain 7-8 grams of steam.
On the i-d diagram, moisture content is depicted by vertical lines, and gradation information is located at the bottom of the diagram:
(to enlarge the picture, click and then click on it again)
The second important element to understand is air temperature (T or t). I think there is no need to explain anything here. On most ID charts, this value is measured in degrees Celsius [°C]. On the i-d diagram, temperature is depicted by inclined lines, and information about the gradation is located on the left side of the diagram:
(to enlarge the picture, click and then click on it again)
The third element of the ID diagram is relative humidity (φ). Relative humidity is exactly the humidity that we hear about on TV and radio when we listen to the weather forecast. It is measured in percentage [%].
A reasonable question arises: “What is the difference between relative humidity and moisture content?” I will answer this question step by step:
First stage:
Air can hold a certain amount of steam. Air has a certain “steam carrying capacity”. For example, in your room, a kilogram of air can “take on board” no more than 15 grams of steam.
Let's assume that your room is comfortable, and each kilogram of air in your room contains 8 grams of steam, and each kilogram of air can contain 15 grams of steam. As a result, we get that there is 53.3% of the maximum possible vapor in the air, i.e. relative air humidity - 53.3%.
Second phase:
Air capacity varies at different temperatures. The higher the air temperature, the more steam it can contain; the lower the temperature, the lower the capacity.
Let's assume that we heated the air in your room with a conventional heater from +20 degrees to +30 degrees, but the amount of steam in each kilogram of air remained the same - 8 grams. At +30 degrees, the air can “take on board” up to 27 grams of steam, as a result, in our heated air there is 29.6% of the maximum possible steam, i.e. relative air humidity - 29.6%.
The same goes for cooling. If we cool the air to +11 degrees, we get a “carrying capacity” of 8.2 grams of steam per kilogram of air and a relative humidity of 97.6%.
Note that there was the same amount of moisture in the air - 8 grams, and the relative humidity jumped from 29.6% to 97.6%. This happened due to temperature fluctuations.
When you hear about the weather on the radio in winter, where they say that it is minus 20 degrees outside and the humidity is 80%, this means that there is about 0.3 grams of steam in the air. When this air enters your apartment, it heats up to +20 and the relative humidity of such air becomes equal to 2%, and this is very dry air (in fact, in an apartment in winter the humidity is kept at 20-30% due to moisture released from the bathrooms and from people, but that is also below the comfort parameters).
Third stage:
What happens if we lower the temperature to a level where the “carrying capacity” of the air is lower than the amount of vapor in the air? For example, up to +5 degrees, where the air capacity is 5.5 grams/kilogram. That part of gaseous H2O that does not fit into the “body” (for us it is 2.5 grams) will begin to turn into liquid, i.e. in water. In everyday life, this process is especially clearly visible when windows fog up due to the fact that the glass temperature is lower than average temperature in the room, so much so that there is little room for moisture in the air and steam, turning into liquid, settles on the glass.
On an i-d diagram, relative humidity is depicted by curved lines, and gradation information is located on the lines themselves:(to enlarge the picture, click and then click on it again)
Fourth elementID diagrams - enthalpy (I ori). Enthalpy contains the energy component of the heat and humidity state of the air. With further study (beyond the scope of this article), it is worth paying special attention to it when it comes to dehumidifying and humidifying the air. But for now we will not focus special attention on this element. Enthalpy is measured in [kJ/kg]. On an i-d diagram, enthalpy is depicted as slanted lines, and gradation information is located on the graph itself (or on the left and at the top of the diagram):
(to enlarge the picture, click and then click on it again)
Then everything is simple! The chart is easy to use! Let's take, for example, your comfortable room, in which the temperature is +20°C and the relative humidity is 50%. We find the intersection of these two lines (temperature and humidity) and see how many grams of steam are in our air.
We heat the air to +30°C - the line goes up, because... There is still the same amount of moisture in the air, but only the temperature increases. We put an end to it and see what the relative humidity turns out to be - it turned out to be 27.5%.
We cool the air to 5 degrees - again we draw a vertical line down, and in the region of +9.5 ° C we come across a line of 100% relative humidity. This point is called the “dew point” and at this point (theoretically, since in practice deposition begins a little earlier) condensation begins to form. We cannot move lower along a vertical straight line (as before), because at this point the “carrying capacity” of air at a temperature of +9.5°C is maximum. But we need to cool the air to +5°C, so we continue to move along the relative humidity line (shown in the figure below) until we reach a slanted straight line of +5°C. As a result, our final point was at the intersection of the +5°C temperature line and the 100% relative humidity line. Let's see how much steam is left in our air - 5.4 grams in one kilogram of air. And the remaining 2.6 grams were released. Our air has become dry.(to enlarge the picture, click and then click on it again)
Other processes that can be performed with air using various devices (dehumidification, cooling, humidification, heating...) can be found in textbooks.
Besides the dew point, another important point is the “wet bulb temperature”. This temperature is actively used in the calculation of cooling towers. Roughly speaking, this is the point to which the temperature of an object can drop if we wrap this object in a wet rag and begin to “blow” intensively on it, for example, using a fan. The human thermoregulation system operates on this principle.
How to find this point? For these purposes we will need enthalpy lines. Let's take our comfortable room again, find the point of intersection of the temperature line +20°C and relative humidity 50%. From this point it is necessary to draw a line parallel to the enthalpy lines up to the 100% humidity line (as in the figure below). The point of intersection of the enthalpy line and the relative humidity line will be the point of the wet thermometer. In our case, from this point we can find out what is in our room, so we can cool the object to a temperature of +14°C.(to enlarge the picture, click and then click on it again)
The process ray (angular coefficient, heat-moisture ratio, ε) is constructed in order to determine the change in air from the simultaneous release of heat and moisture by a certain source(s). Usually this source is a person. An obvious thing, but understanding processes i-d diagrams will help to detect a possible arithmetic error, if one occurs. For example, if you plot a beam on a diagram and, under normal conditions and the presence of people, your moisture content or temperature decreases, then it’s worth thinking about and checking the calculations.
In this article, much is simplified for a better understanding of the diagram at the initial stage of studying it. More accurate, more detailed and more scientific information must be sought in educational literature.
P. S. In some sources2018-05-15
IN Soviet time in textbooks on ventilation and air conditioning, as well as among design engineers and adjusters, the i–d diagram was usually referred to as the “Ramzin diagram” - in honor of Leonid Konstantinovich Ramzin, a major Soviet heating scientist, whose scientific and technical activities were multifaceted and covered a wide range scientific issues of thermal engineering. At the same time, in most Western countries it has always been called the “Molier diagram”...
i-d- diagram as a perfect tool
June 27, 2018 marks the 70th anniversary of the death of Leonid Konstantinovich Ramzin, a prominent Soviet heating engineer whose scientific and technical activities were multifaceted and covered a wide range of scientific issues in heat engineering: the theory of design of thermal power and electric power plants, aerodynamic and hydrodynamic calculations of boiler plants, combustion and radiation of fuel in furnaces, theories of the drying process, as well as solutions to many practical problems, for example, the efficient use of coal from the Moscow region as fuel. Before Ramzin’s experiments, this coal was considered inconvenient to use.
One of Ramzin’s many works was devoted to the issue of mixing dry air and water vapor. Analytical calculation of the interaction of dry air and water vapor is a rather complex mathematical problem. But there is i-d- diagram. Its use simplifies the calculation in the same way as i-s- The diagram reduces the complexity of calculating steam turbines and other steam machines.
Today it is difficult to imagine the work of a designer or commissioning engineer for air conditioning without using i-d- diagrams. With its help, you can graphically represent and calculate air treatment processes, determine the power of refrigeration units, analyze in detail the process of drying materials, and determine the state of moist air at each stage of its processing. The diagram allows you to quickly and clearly calculate the air exchange of a room, determine the need for air conditioners for cold or heat, measure the condensate flow rate during operation of the air cooler, calculate the required water flow rate for adiabatic cooling, and determine the dew point temperature or wet thermometer temperature.
In Soviet times, in textbooks on ventilation and air conditioning, as well as among design engineers and adjusters i-d- the diagram was usually referred to as the "Ramzin diagram". At the same time, in a number of Western countries - Germany, Sweden, Finland and many others - it has always been called the “Molier diagram”. Over time, technical capabilities i-d- The diagrams were constantly expanded and improved. Today, thanks to it, calculations are made of the conditions of humid air in conditions variable pressure, air oversaturated with moisture, in foggy areas, near the surface of ice, etc. .
First message about i-d- The diagram appeared in 1923 in one of the German magazines. The author of the article was the famous German scientist Richard Mollier. Several years passed, and suddenly in 1927 an article by the director of the institute, Professor Ramzin, appeared in the journal of the All-Union Thermal Engineering Institute, in which he, practically repeating i-d- diagram from a German magazine and all the analytical calculations given there by Mollier, declares himself the author of this diagram. Ramzin explains this by the fact that back in April 1918, in Moscow, at two public lectures at the Polytechnic Society, he demonstrated a similar diagram, which at the end of 1918 was published by the Thermal Committee of the Polytechnic Society in lithographed form. In this form, Ramzin writes, in 1920 the diagram was widely used by him at the Moscow Higher Technical School as a teaching aid when giving lectures.
Modern admirers of Professor Ramzin would like to believe that he was the first to develop the diagram, so in 2012 a group of teachers from the Department of Heat, Gas Supply and Ventilation of the Moscow State Academy public utilities and construction tried to find documents in various archives confirming the facts of primacy stated by Ramzin. Unfortunately, no clarifying materials for the period 1918-1926 could be found in the archives available to teachers.
True, it should be noted that the period of Ramzin’s creative activity fell on a difficult time for the country, and some rotoprinted publications, as well as drafts of lectures on the diagram, could have been lost, although the rest of his scientific developments, even handwritten ones, were well preserved.
None of Professor Ramzin’s former students, except M. Yu. Lurie, also left any information about the diagram. Only engineer Lurie, as the head of the drying laboratory of the All-Union Thermal Engineering Institute, supported and complemented his boss, Professor Ramzin, in an article published in the same VTI journal for 1927.
When calculating the parameters of moist air, both authors, L.K. Ramzin and Richard Mollier, believed with a sufficient degree of accuracy that the laws of ideal gases could be applied to moist air. Then, according to Dalton's law, the barometric pressure of moist air can be represented as the sum of the partial pressures of dry air and water vapor. And solving the system of Clayperon equations for dry air and water vapor allows us to establish that the moisture content of air at a given barometric pressure depends only on the partial pressure of water vapor.
Both the Mollier and Ramzin diagrams are constructed in an oblique coordinate system with an angle of 135° between the enthalpy and moisture content axes and are based on the equation for the enthalpy of moist air per 1 kg of dry air: i = i c + i P d, Where i c and i n is the enthalpy of dry air and water vapor, respectively, kJ/kg; d— air moisture content, kg/kg.
According to Mollier and Ramzin, relative air humidity is the ratio of the mass of water vapor in 1 m³ of humid air to the maximum possible mass of water vapor in the same volume of this air at the same temperature. Or, approximately, relative humidity can be represented as the ratio of the partial vapor pressure in air in an unsaturated state to the partial vapor pressure in the same air in a saturated state.
Based on the above theoretical premises in a system of oblique coordinates, an i-d diagram was compiled for a certain barometric pressure.
The ordinate axis shows the enthalpy values, the abscissa axis, directed at an angle of 135° to the ordinate, shows the moisture content of dry air, and also shows the lines of temperature, moisture content, enthalpy, relative humidity, and a scale of partial pressure of water vapor.
As stated above, i-d-the diagram was compiled for a certain barometric pressure of humid air. If the barometric pressure changes, then on the diagram the moisture content and isotherm lines remain in their places, but the values of the relative humidity lines change in proportion to the barometric pressure. So, for example, if the barometric air pressure decreases by half, then on the i-d diagram on the relative humidity line of 100% you should write a humidity of 50%.
The biography of Richard Mollier confirms that i-d-the diagram was not the first calculation diagram he compiled. He was born on November 30, 1863 in the Italian city of Trieste, which was part of the multinational Austrian Empire, ruled by the Habsburg Monarchy. His father, Edouard Mollier, was first a ship engineer, then became the director and co-owner of a local engineering factory. Mother, née von Dick, came from an aristocratic family from the city of Munich.
After graduating from high school in Trieste with honors in 1882, Richard Mollier began studying first at the university in Graz, and then transferred to the University of Munich Technical University, where he paid a lot of attention to mathematics and physics. His favorite teachers were professors Maurice Schröter and Karl von Linde. After successfully completing his studies at the university and a short engineering practice at his father's company, Richard Mollier was enrolled as an assistant to Maurice Schröter at the University of Munich in 1890. His first scientific work in 1892, under the direction of Maurice Schröter, was related to the construction of thermal diagrams for a course in the theory of machines. Three years later, Mollier defended his doctoral dissertation on the entropy of steam.
From the very beginning, Richard Mollier's interests were focused on the properties of thermodynamic systems and the possibility of reliably representing theoretical developments in the form of graphs and diagrams. Many of his colleagues considered him a pure theorist because, instead of conducting his own experiments, he relied on the empirical data of others in his research. But in fact, he was a kind of “link” between theorists (Rudolph Clausius, J.W. Gibbs, etc.) and practical engineers. In 1873, Gibbs proposed as an alternative to analytical calculations t-s- a diagram in which the Carnot cycle turned into a simple rectangle, making it possible to easily assess the degree of approximation of real thermodynamic processes in relation to ideal ones. For the same diagram in 1902, Mollier proposed using the concept of “enthalpy” - a certain state function that was still little known at that time. The term “enthalpy” was previously, at the suggestion of the Dutch physicist and chemist Heike Kamerlingh-Onnes (Nobel Prize winner in physics 1913), first introduced into the practice of thermal calculations by Gibbs. Like "entropy" (a term coined in 1865 by Clausius), enthalpy is an abstract property that cannot be directly measured.
The great advantage of this concept is that it allows us to describe the change in energy of a thermodynamic medium without taking into account the difference between heat and work. Using this state function, Mollier proposed a diagram in 1904 showing the relationship between enthalpy and entropy. In our country it is known as i-s- diagram. This diagram, while retaining most of the advantages t-s-diagrams provide some additional possibilities and make it surprisingly simple to illustrate the essence of both the first and second laws of thermodynamics. Investing in a large-scale reorganization of thermodynamic practice, Richard Mollier developed a whole system of thermodynamic calculations based on the use of the concept of enthalpy. As a basis for these calculations, he used various graphs and diagrams of the properties of steam and a number of refrigerants.
In 1905, the German researcher Müller, to visually study the processes of processing moist air, constructed a diagram in a rectangular coordinate system of temperature and enthalpy. Richard Mollier improved this diagram in 1923, making it oblique with axes of enthalpy and moisture content. In this form, the diagram has practically survived to this day. During his life, Mollier published the results of a number of important studies on thermodynamics and trained a galaxy of outstanding scientists. His students, such as Wilhelm Nusselt, Rudolf Planck and others, made a number of fundamental discoveries in the field of thermodynamics. Richard Mollier died in 1935.
L.K. Ramzin was 24 years younger than Mollier. His biography is interesting and tragic. It is closely connected with the political and economic history of our country. He was born on October 14, 1887 in the village of Sosnovka, Tambov region. His parents, Praskovya Ivanovna and Konstantin Filippovich, were teachers of the zemstvo school. After graduating from the Tambov gymnasium with a gold medal, Ramzin entered the Higher Imperial Technical School (later MVTU, now MSTU). While still a student, he takes part in scientific works under the guidance of Professor V.I. Grinevetsky. In 1914, having completed his studies with honors and receiving a diploma as a mechanical engineer, he was left at the school for scientific and teaching work. Less than five years had passed before the name of L.K. Ramzin began to be mentioned in the same breath as such famous Russian heating scientists as V.I. Grinevetsky and K.V. Kirsch.
In 1920, Ramzin was elected professor at Moscow Higher Technical University, where he headed the departments of “Fuel, furnaces and boiler plants” and “Thermal stations”. In 1921, he became a member of the country's State Planning Committee and was involved in work on the GOERLO plan, where his contribution was exceptionally significant. At the same time, Ramzin is an active organizer of the creation of the Thermotechnical Institute (VTI), of which he was director from 1921 to 1930, as well as its scientific director from 1944 to 1948. In 1927 he was appointed a member All-Union Council National Economy (VSNKh), is involved in large-scale issues of heat supply and electrification of the entire country, goes on important foreign business trips: to England, Belgium, Germany, Czechoslovakia, and the USA.
But the situation in the country in the late 1920s was heating up. After Lenin's death, the struggle for power between Stalin and Trotsky sharply intensified. The warring parties delve into the jungle of antagonistic disputes, conjuring each other in the name of Lenin. Trotsky, as People's Commissar of Defense, has the army on his side, he is supported by trade unions led by their leader M.P. Tomsky, who opposes Stalin's plan to subordinate the trade unions to the party, defending the autonomy of the trade union movement. On Trotsky’s side are almost the entire Russian intelligentsia, who are dissatisfied with the economic failures and devastation in the country of victorious Bolshevism.
The situation is favorable to the plans of Leon Trotsky: disagreements have emerged in the leadership of the country between Stalin, Zinoviev and Kamenev, and Trotsky’s main enemy, Dzerzhinsky, is dying. But Trotsky at this time does not use his advantages. Opponents, taking advantage of his indecisiveness, removed him from the post of People's Commissar of Defense in 1925, depriving him of control over the Red Army. After some time, Tomsky was released from leadership of the trade unions.
Trotsky's attempt on November 7, 1927, on the day of the tenth anniversary October revolution, they failed to bring their supporters onto the streets of Moscow.
And the situation in the country continues to deteriorate. The failures and setbacks of socio-economic policy in the country force the party leadership of the USSR to shift the blame for disruptions in the pace of industrialization and collectivization to the “pests” from among the “class enemies”.
By the end of the 1920s, industrial equipment that had remained in the country since tsarist times, having survived the revolution, civil war and economic ruin, was in a deplorable state. The result of this was an increasing number of accidents and disasters in the country: in the coal industry, in transport, in urban areas and other areas. And since there are disasters, there must be culprits. A solution was found: the technical intelligentsia—sabotage engineers—are to blame for all the troubles happening in the country. The same ones who tried with all their might to prevent these troubles. Engineers began to be judged.
The first was the high-profile “Shakhty case” of 1928, followed by trials by the People’s Commissariat of Railways and the gold mining industry.
Now it’s the turn of the “Industrial Party case” - a major trial based on fabricated materials in the case of sabotage in 1925-1930 in industry and transport, allegedly conceived and carried out by an anti-Soviet underground organization known as the “Union of Engineering Organizations”, “Council of the Union of Engineering Organizations” ", "Industrial Party".
According to the investigation, the central committee of the “Industrial Party” included engineers: P. I. Palchinsky, who was shot by the verdict of the OGPU board in the case of sabotage in the gold-platinum industry, L. G. Rabinovich, who was convicted in the “Shakhtinsky case”, and S.A. Khrennikov, who died during the investigation. After them, Professor L.K. Ramzin was declared the head of the Industrial Party.
And so in November 1930 in Moscow, in the Hall of Columns of the House of Unions, a special judicial presence of the Supreme Soviet of the USSR, chaired by prosecutor A. Ya. Vyshinsky, began an open hearing on the case of the counter-revolutionary organization "Union of Engineering Organizations" ("Industrial Party"), the leadership center and whose financing was allegedly located in Paris and consisted of former Russian capitalists: Nobel, Mantashev, Tretyakov, Ryabushinsky and others. The main prosecutor at the trial is N.V. Krylenko.
There are eight people in the dock: heads of departments of the State Planning Committee, the largest enterprises and educational institutions, professors at academies and institutes, including Ramzin. The prosecution claims that the Industrial Party was planning a coup d'etat, that the accused even distributed positions in the future government - for example, millionaire Pavel Ryabushinsky was planned for the post of Minister of Industry and Trade, with whom Ramzin, while on a business trip abroad in Paris, allegedly conducted secret negotiations. After the publication of the indictment, foreign newspapers reported that Ryabushinsky died back in 1924, long before possible contact with Ramzin, but such reports did not bother the investigation.
This process differed from many others in that the state prosecutor Krylenko did not play the most important role here; he could not provide any documentary evidence, since there was none in nature. In fact, Ramzin himself became the main accuser, who confessed to all the charges brought against him, and also confirmed the participation of all those accused in counter-revolutionary actions. In fact, Ramzin was the author of the accusations of his comrades.
As open archives show, Stalin closely followed the progress of the trial. This is what he writes in mid-October 1930 to the head of the OGPU V.R. Menzhinsky: “ My proposals: make one of the most important key points in the testimony of the top of the TKP “Industrial Party” and especially Ramzin the question of intervention and the timing of the intervention... it is necessary to involve other members of the Central Committee of the “Industrial Party” in the case and interrogate them most strictly about the same thing, letting them read Ramzin’s testimony ...».
All of Ramzin's confessions were used as the basis for the indictment. At the trial, all the accused confessed to all the crimes that were charged against them, including their connection with the French Prime Minister Poincaré. The head of the French government issued a refutation, which was even published in the newspaper Pravda and announced at the trial, but as a consequence this statement was added to the case as a statement by a well-known opponent of communism, proving the existence of a conspiracy. Five of the accused, including Ramzin, were sentenced to death, then commuted to ten years in the camps, the other three - to eight years in the camps. All of them were sent to serve their sentences, and all of them, except Ramzin, died in the camps. Ramzin was given the opportunity to return to Moscow and, in conclusion, continue his work on the calculation and design of a high-power once-through boiler.
To implement this project in Moscow, on the basis of the Butyrskaya prison in the area of the current Avtozavodskaya street, a “Special design bureau for direct-flow boiler construction” (one of the first “sharashkas”) was created, where, under the leadership of Ramzin, with the involvement of free specialists from the city, design work was carried out. By the way, one of the free engineers involved in this work was the future professor at the V.V. Kuibyshev MISI M.M. Shchegolev.
And so on December 22, 1933, Ramzin’s direct-flow boiler, manufactured at the Nevsky Machine-Building Plant named after. Lenin, with a capacity of 200 tons of steam per hour, having a working pressure of 130 atm and a temperature of 500 °C, was put into operation in Moscow at the TPP-VTI (now TPP-9). Several similar boiler houses based on Ramzin’s design were built in other areas. In 1936, Ramzin was completely released. He became the head of the newly created department of boiler engineering at the Moscow Energy Institute, and was also appointed scientific director of VTI. The authorities awarded Ramzin the Stalin Prize of the first degree, the Order of Lenin and the Red Banner of Labor. At that time, such awards were very highly valued.
The USSR Higher Attestation Commission awarded L.K. Ramzin the academic degree of Doctor of Technical Sciences without defending a dissertation.
However, the public did not forgive Ramzin for his behavior at the trial. An ice wall appeared around him; many colleagues did not shake hands with him. In 1944, on the recommendation of the science department of the Central Committee of the All-Union Communist Party of Bolsheviks, he was nominated as a corresponding member of the USSR Academy of Sciences. In a secret vote at the Academy, he received 24 votes against and only one in favor. Ramzin was completely broken, morally destroyed, his life was over. He died in 1948.
Comparing the scientific developments and biographies of these two scientists, who worked almost at the same time, we can assume that i-d- The diagram for calculating the parameters of humid air was most likely born on German soil. It is surprising that Professor Ramzin began to claim authorship i-d- diagrams only four years after the appearance of Richard Mollier’s article, although he always closely followed new technical literature, including foreign ones. In May 1923, at a meeting of the Thermotechnical Section of the Polytechnic Society of the All-Union Association of Engineers, he even gave a scientific report on his trip to Germany. Being aware of the work of German scientists, Ramzin probably wanted to use them in his homeland. It is possible that he made parallel attempts to conduct similar scientific and practical work at the Moscow Higher Technical School in this area. But not a single application article on i-d-the diagram has not yet been found in the archives. Drafts of his lectures on thermal power plants, on testing various fuel materials, on the economics of condensing units, etc. have been preserved. And not a single, not even a draft entry on i-d-a diagram written by him before 1927 has not yet been found. So, despite patriotic feelings, we have to conclude that the author i-d-diagram is precisely by Richard Mollier.
- Nesterenko A.V., Fundamentals of thermodynamic calculations of ventilation and air conditioning. - M.: graduate School, 1962.
- Mikhailovsky G.A. Thermodynamic calculations of processes of vapor-gas mixtures. - M.-L.: Mashgiz, 1962.
- Voronin G.I., Verbe M.I. Air conditioning on aircraft. - M.: Mashgiz, 1965.
- Prokhorov V.I. Air conditioning systems with air refrigeration machines. - M.: Stroyizdat, 1980.
- Mollier R. Ein neues. Diagramm fu?r Dampf-Luftgemische. Zeitschrift des Vereins Deutscher Ingenieure. 1923. No. 36.
- Ramzin L.K. Calculation of dryers in the i-d diagram. - M.: News of the Heat Engineering Institute, No. 1(24). 1927.
- Gusev A.Yu., Elkhovsky A.E., Kuzmin M.S., Pavlov N.N. The mystery of the i-d diagram // ABOK, 2012. No. 6.
- Lurie M.Yu. A method for constructing an i–d diagram by Professor L.K. Ramzin and auxiliary tables for humid air. - M.: News of the Heat Engineering Institute, 1927. No. 1 (24).
- A blow to the counter-revolution. Indictment in the case of the counter-revolutionary organization of the Union of Engineering Organizations (“Industrial Party”). - M.-L., 1930.
- Process of the “Industrial Party” (from 11/25/1930 to 12/07/1930). Transcript of the trial and materials attached to the case. - M., 1931.
For practical purposes, it is most important to calculate the cooling time of the cargo using the equipment available on board the ship. Since the capabilities of a ship's gas liquefaction plant largely determine the time a ship stays in a port, knowledge of these capabilities will allow you to plan your stay time in advance and avoid unnecessary downtime, and therefore claims against the ship.
Mollier diagram. which is given below (Fig. 62), is calculated only for propane, but the method of its use is the same for all gases (Fig. 63).
The Mollier chart uses a logarithmic absolute pressure scale (R log) - on the vertical axis, on the horizontal axis h - natural scale of specific enthalpy (see Fig. 62, 63). Pressure is in MPa, 0.1 MPa = 1 bar, so in the future we will use bars. Specific enthalpy is measured in p kJ/kg. In the future, when solving practical problems, we will constantly use the Mollier diagram (but only its schematic representation in order to understand the physics of thermal processes occurring with the load).
In the diagram you can easily notice a kind of “net” formed by the curves. The boundaries of this “net” are outlined by the boundary curves of changes in the aggregate states of liquefied gas, which reflect the transition of LIQUID TO saturated vapor. Everything that is to the left of the “net” refers to supercooled liquid, and everything that is to the right of the “net” refers to superheated steam (see Fig. 63).
The space between these curves represents different states of the mixture of saturated propane vapor and liquid, reflecting the process of phase transition. Using a number of examples, we will consider the practical use* of the Mollier diagram.
Example 1: Draw a line corresponding to a pressure of 2 bar (0.2 MPa) through the section of the diagram reflecting the phase change (Fig. 64).
To do this, we determine the enthalpy for 1 kg of boiling propane at an absolute pressure of 2 bar.
As noted above, boiling liquid propane is characterized by the left curve of the diagram. In our case this will be a point A, Swiping from a point A vertical line to scale A, we determine the enthalpy value, which will be 460 kJ/kg. This means that each kilogram of propane in this state (at its boiling point at 2 bar pressure) has an energy of 460 kJ. Therefore, 10 kg of propane will have an enthalpy of 4600 kJ.
Next, we determine the enthalpy value for dry saturated propane steam at the same pressure (2 bar). To do this, draw a vertical line from the point IN until it intersects with the enthalpy scale. As a result, we find that the maximum enthalpy value for 1 kg of propane in the saturated vapor phase will be 870 kJ. Inside the chart
* For calculations, data from thermodynamic tables of propane are used (see Appendices).
Rice. 64. For example 1 Fig. 65. For example 2
U 
unit enthalpy, kJ/kg (kcal/kg)
Rice. 63. Basic curves of the Mollier diagram
(Fig. 65) lines directed downwards from the point of critical state of the gas display the number of parts of gas and liquid in the transition phase. In other words, 0.1 means that the mixture contains 1 part gas vapor and 9 parts liquid. At the point of intersection of the saturated vapor pressure and these curves, we determine the composition of the mixture (its dryness or humidity). The transition temperature is constant throughout the entire condensation or vaporization process. If propane is in a closed system (cargo tank), it contains both liquid and gaseous phases of the cargo. You can determine the temperature of a liquid by knowing the vapor pressure, and the vapor pressure by knowing the temperature of the liquid. Pressure and temperature are related if liquid and vapor are in equilibrium in a closed system. Note that the temperature curves located on the left side of the diagram go down almost vertically, cross the vaporization phase in the horizontal direction, and on the right side of the diagram go down again almost vertically.
Example 2: Suppose that there is 1 kg of propane in the phase change stage (part of the propane is liquid, and part is steam). The saturated vapor pressure is 7.5 bar and the enthalpy of the mixture (vapor-liquid) is 635 kJ/kg.
It is necessary to determine what part of the propane is in the liquid phase and what part is in the gaseous phase. Let us first display the known values on the diagram: vapor pressure (7.5 bar) and enthalpy (635 kJ/kg). Next, we determine the intersection point of pressure and enthalpy - it lies on the curve, which is designated 0.2. And this, in turn, means that we have propane in the boiling stage, with 2 (20%) parts of propane being in a gaseous state, and 8 (80%) being in a liquid state.
You can also determine the gauge pressure of a liquid in a tank whose temperature is 60° F, or 15.5° C (to convert the temperature we will use the table of the thermodynamic characteristics of propane from the Appendix).
It must be remembered that this pressure is less than the saturated vapor pressure (absolute pressure) by the amount of atmospheric pressure equal to 1.013 mbar. In the future, to simplify calculations, we will use an atmospheric pressure value of 1 bar. In our case, the vapor pressure, or absolute pressure, is 7.5 bar, so the gauge pressure in the tank will be 6.5 bar.
Rice. 66. For example 3
It was already mentioned earlier that liquid and vapor are in equilibrium in a closed system at the same temperature. This is true, but in practice you can notice that the vapors located in the upper part of the tank (in the dome) have a temperature much higher than the temperature of the liquid. This is due to the heating of the tank. However, such heating does not affect the pressure in the tank, which corresponds to the temperature of the liquid (more precisely, the temperature at the surface of the liquid). The vapors directly above the surface of the liquid have the same temperature as the liquid itself on the surface, where the phase change of the substance occurs.As can be seen from Fig. 62-65, on the Mollier diagram the density curves are directed from the lower left corner of the net diagram to the upper right corner. The density value on the diagram can be given in Ib/ft 3 . For conversion to SI, a conversion factor of 16.02 is used (1.0 Ib/ft 3 = 16.02 kg/m 3).
Example 3: In this example we will use density curves. It is required to determine the density of superheated propane vapor at an absolute pressure of 0.95 bar and a temperature of 49°C (120°F). 
We will also determine the specific enthalpy of these vapors.
The solution to the example can be seen in Figure 66.
Our examples use the thermodynamic characteristics of one gas - propane.
In such calculations, only the absolute values of the thermodynamic parameters will change for any gas, but the principle remains the same for all gases. In the future, to simplify, increase the accuracy of calculations and reduce time, we will use tables of the thermodynamic properties of gases.
Almost all the information included in the Mollier diagram is presented in tabular form.
WITH 
Using tables you can find the values of the cargo parameters, but it is difficult. Rice. 67. For example 4 imagine how the process goes. . cooling, if you do not use at least a schematic diagram display p-
h.
Example 4: There is propane in a cargo tank at a temperature of -20" C. It is necessary to determine as accurately as possible the gas pressure in the tank at a given temperature. Next, it is necessary to determine the density and enthalpy of vapor and liquid, as well as the difference in enthalpy between liquid and vapor. Vapors above the surface of the liquid are in a state of saturation at the same temperature as the liquid itself. Atmospheric pressure is 980 mlbar. It is necessary to construct a simplified Mollier diagram and display all the parameters on it.
Using the table (see Appendix 1), we determine the saturated vapor pressure of propane. The absolute vapor pressure of propane at a temperature of -20° C is 2.44526 bar. The pressure in the tank will be equal to:
pressure in the tank (gage or gauge)
1.46526 bar
atmospheric pressure= 0.980 bar =
Absolute_pressure
2.44526 bar
In the column corresponding to the density of the liquid, we find that the density of liquid propane at -20° C will be 554.48 kg/m 3 . Next, we find in the corresponding column the density of saturated vapors, which is equal to 5.60 kg/m3. The liquid enthalpy will be 476.2 kJ/kg, and the vapor enthalpy will be 876.8 kJ/kg. Accordingly, the enthalpy difference will be (876.8 - 476.2) = 400.6 kJ/kg.
A little later we will consider the use of the Mollier diagram in practical calculations to determine the operation of re-liquefaction plants.
Considering what is the main object of the ventilation process, in the field of ventilation it is often necessary to determine certain air parameters. To avoid numerous calculations, they are usually determined using a special diagram called the Id diagram. It allows you to quickly determine all air parameters using two known ones. Using a diagram allows you to avoid calculations using formulas and visually display the ventilation process. An example of an Id chart is shown on the next page. The analogue of the Id chart in the west is Mollier diagram or psychrometric chart.
The design of the diagram can, in principle, be somewhat different. A typical general diagram of an Id diagram is shown below in Figure 3.1. The diagram is a working field in the oblique coordinate system Id, on which several coordinate grids are plotted and auxiliary scales along the perimeter of the diagram. The moisture content scale is usually located along the bottom edge of the diagram, with the constant moisture content lines representing vertical straight lines. The constant lines represent parallel straight lines, usually running at an angle of 135° to the vertical moisture content lines (in principle, the angles between the enthalpy and moisture content lines can be different). The oblique coordinate system was chosen in order to increase the working area of the diagram. In such a coordinate system the lines constant temperatures are straight lines running at a slight inclination to the horizontal and slightly fanning out.
The working field of the diagram is limited by curved lines of equal relative humidity 0% and 100%, between which lines of other values of equal relative humidity are plotted with a step of 10%.
The temperature scale is usually located along the left edge of the working area of the diagram. The values of air enthalpies are usually plotted under the curve Ф = 100. The values of partial pressures are sometimes plotted along the upper edge of the working field, sometimes along the lower edge under the moisture content scale, sometimes along the right edge. In the latter case, an auxiliary partial pressure curve is additionally plotted on the diagram.
