Under specific heat Substances understand the amount of heat that need to be informed or take away from the unit of substance (1 kg, 1 m 3, 1 mol) to change its temperature per degree.

Depending on the unit of a given substance, the following specific heat capacity distinguishes:

Mass heat capacity FROM, assigned to 1 kg of gas, J / (kg ∙ k);

Molar heat capacity μs, assigned to 1 km and Gaza, J / (Kolol ∙ K);

Volumetric heat FROM', assigned to 1 m 3 Gas, J / (m 3 ∙ K).

Specific heat capacity are related to each other by the ratio:

where υ N. - specific gas volume under normal conditions (N.U.), m 3 / kg; µ - molar weight of gas, kg / kmol.

The heat capacity of the ideal gas depends on the nature of the process of supplying (or removal) heat, from the gas atomic and temperature (the heat capacity of real gases also depends on pressure).

Communication between mass isobar With P. and isochorny With V. The heat capacity is set by the Mayer equation:

With p - with v \u003d r, (1.2)

where R -gas constant, J / (kg ∙ K).

When the ideal gas is heated in a closed vessel, the constant volume of heat is consumed only on the change in the motion energy of its molecules, and when heated at constant pressure, due to the expansion of the gas, work is performed at the same time against external forces.

For molar heat capacity, the Mayer equation has the form:

μС P - μS v \u003d μr, (1.3)

where μR\u003d 8314J / (kmol ∙ K) - universal gas constant.

The volume of perfect gas V N.provided to normal conditions is determined from the following relationship:

(1.4)

where R N. - pressure under normal conditions, R N. \u003d 101325 Pa \u003d 760 mm RTST; T N. - temperature under normal conditions T N. \u003d 273.15 k; P T., V T., T T. - Working pressure, volume and temperature of gas.

The ratio of the isobaric heat capacity to isochlorine is denoted k. and called indicator adiabat:

(1.5)

From (1.2) and taking into account (1.5) we get:

For accurate calculations, the average heat capacity is determined by the formula:

(1.7)

In thermal calculations of various equipment, the amount of heat is often determined, which is required for heating or cooling gases:

Q \u003d C ∙ M∙(t. 2 - t. 1), (1.8)

Q \u003d C '∙ V n∙(t. 2 - t. 1), (1.9)

where V N. - Gas volume at N.U., M 3.

Q \u003d μc ∙ ν∙(t. 2 - t. 1), (1.10)

where ν - Number of gas, kmol.

Heat capacity. Using heat capacity to describe processes in closed systems

In accordance with equation (4.56), the heat can be determined if the change in the entropy S system is known. However, the fact that entropy cannot be measured directly, creates some complications, especially when describing isochorny and isobaric processes. There is a need to determine the amount of heat using the values \u200b\u200bmeasured by the experience.

The heat capacity of the system can act as such a magnitude. The most general definition of heat capacity implies from the expression of the first law of thermodynamics (5.2), (5.3). Based on it, any capacity of the system with respect to the operation of the form M is determined by the equation

C m \u003d da m / dp m \u003d p M d e g m / dp m, (5.42)

where with m is the capacity of the system;

P M and G M - respectively, the generalized potential and the coordinate of the state of the form M.

The value of C M shows how much type M work must be made under the given conditions to change the Mr. Generalized potential of the system per unit of measurement.

The concept of the capacity of the system with respect to one or another work in thermodynamics is widely used only when describing thermal interaction between the system and the environment.

The system capacity in relation to heat is called heat capacity and is given by equality.

C \u003d D E Q / DT \u003d TD E S heat / dt. (5.43)

In this way, the heat capacity can be defined as the amount of heat that must be reported to the system to change its temperature for one Kelvin.

The heat capacity, like internal energy and enthalpy, is an extensive value proportional to the amount of substance.In practice, heat capacity is used, subject to a unit of mass of substance - specific heat, and heat capacity assigned to one praying substance - molar heat capacity. The specific heat capacity in C is expressed in J / (kg · k), and the molar is in J / (mol · k).

Specific and molar heat capacity are associated with the ratio:

With mol \u003d c ud m, (5.44)

where M is the molecular weight of the substance.

Distinguish true (differential) heat capacitydetermined from equation (5.43) and representing the elementary increment of heat at an infinitely small temperature change, and average heat capacity representing the ratio of the total amount of heat to the full change in temperature in this process:

Q / DT. (5.45)

The relationship between true and medium specific heat capacity is set by the relation

At constant pressure or volume of heat and, accordingly, the heat capacity acquire properties of the state function, i.e. become characteristics of the system. It is these heat capacity - isobaric with p (at constant pressure) and isochorny with V (with a constant volume) are most widely used in thermodynamics.

If the system is heated at a constant volume, then in accordance with the expression (5.27), the hegoic heat capacity C V is recorded as

C v \u003d . (5.48)

If the system is heated at a constant pressure, then in accordance with equation (5.32), the isobaric heat capacity with p appears as

With p \u003d . (5.49)

To find a link between with P and C v, it is necessary to index the expression (5.31) by temperature. For one mole of the perfect gas, this expression taking into account equation (5.18) can be represented as

H \u003d U + PV \u003d U + RT. (5.50)

dH / DT \u003d DU / DT + R, (5.51)

and the difference between the isobaric and isochoric heat-strokes for one mole of the perfect gas is numerically equal to the universal gas constant R:

C p - with v \u003d r. (5.52)

The heat capacity at constant pressure is always greater than heat capacity at a constant volume, since the heating of the substance at constant pressure is accompanied by the operation of the gas expansion.

Using the expression of the internal energy of the ideal single-osomic gas (5.21), we obtain the value of its heat capacity for one mole of the perfect single-nominal gas:

C v \u003d du / dt \u003d d (3/2 rt) dt \u003d 3/2 R »12.5 J / (mol · k); (5.53)

C p \u003d 3 / 2r + r \u003d 5/2 R »20.8 J / (mol · k). (5.54)

Thus, for single-name ideal gases C V and C, it does not depend on temperature, since the entire thermal energy is consumed only to accelerate the translational movement. For multiatomic molecules, along with a change in the progressive movement, a change in the rotational and oscillatory intramolecular motion can occur. For diatomic molecules, an additional rotational movement is usually taken into account, as a result of which the numerical values \u200b\u200bof their heat-capacity are:

C V \u003d 5/2 R »20.8 J / (mol · K); (5.55)

C p \u003d 5/2 R + R \u003d 7/2 R »29.1 J / (mol · K). (5.56)

Along the way, we will touch the heatabilities of substances in others (except gaseous) aggregate states. To estimate the heat-capacity of solid chemical compounds, the approximate rule of nimane and kopp additivity is often used, according to which the molar heat capacity of chemical compounds in a solid state is equal to the sum of the atomic heat capacity of the elements included in this compound. So, the heat capacity of the complex chemical compound, taking into account the rules of Dulong and PH, can be assessed as:

C v \u003d 25N J / (mol · k), (5.57)

where n is the number of atoms in the molecules of compounds.

The heat capacity of liquids and solid bodies near the melting point (crystallization) is almost equal. Near the normal boiling point, most organic liquids have a specific heat capacity of 1700 - 2100 J / kg · k. In the intervals between these phase transition temperatures, the heat capacity of the liquid can differ significantly (depending on temperature). In general, the dependence of the heat capacity of solid bodies on temperature in the range of 0 - 290k in most cases is well transmitted by the semi-empirical debay equation (for crystalline lattice) in the field of low temperatures

C p »C V \u003d ET 3, (5.58)

in which the proportionality coefficient (E) depends on the nature of the substance (empirical constant).

The dependence of the heat capacity of gases, liquids and solid temperatures during conventional and high temperatures is taken to express with the help of empirical equations having a type of power rows:

C p \u003d A + BT + CT 2 (5.59)

With p \u003d a + bt + c "t -2, (5.60)

where A, B, C and C "is the empirical temperature coefficients.

Returning to the description of the processes in closed systems with the involvement of the method of heat-capacity, we write down some equations given in paragraph 5.1, in several other form.

Isochhore process. Expressing internal energy (5.27) through heat capacity, we get

du v \u003d dq v \u003d u 2 - u 1 \u003d c v dt \u003d c v dt. (5.61)

With the fact that the heat capacity of the ideal gas does not depend on temperature, equation (5.61) can be written as follows:

DU V \u003d Q V \u003d U 2 - U 1 \u003d C V DT. (5.62)

To calculate the value of the integral (5.61) for real single and polyatomic gases, you need to know the specific type of functional dependence C v \u003d f (t) of type (5.59) or (5.60).

The isobaric process. For the gaseous state of the substance, the first law of thermodynamics (5.29) for this process, taking into account the recording of expansion operation (5.35) and using the heat-capacity method is written as follows:

Q p \u003d with v dt + rdt \u003d c p dt \u003d dh (5.63)

Q p \u003d DH P \u003d H 2 - H 1 \u003d C R DT. (5.64)

If the system is perfect gas and the heat capacity with p does not depend on temperature, the relation (5.64) goes into (5.63). To solve equation (5.64), describing real gas, it is necessary to know a specific type of dependence C p \u003d f (t).

Isothermal process. Change in the internal energy of the perfect gas in the process flowing at a constant temperature

du t \u003d c v dt \u003d 0. (5.65)

Adiabatic process. Since Du \u003d C v DT, then for one mole of the perfect gas, the change in internal energy and the work performed is equal, respectively:

Du \u003d c v dt \u003d c v (t 2 - t 1); (5.66)

And the fur \u003d -du \u003d c V (T 1 - T 2). (5.67)

Analysis of equations characterizing various thermodynamic processes under conditions: 1) p \u003d subst; 2) v \u003d subst; 3) T \u003d CONST and 4) DQ \u003d 0 shows that they can all be represented by the general equation:

pV N \u003d SONST. (5.68)

In this equation, the "N" indicator can take values \u200b\u200bfrom 0 to ¥ for different processes:

1. isobaric (n \u003d 0);

2. isothermal (n \u003d 1);

3. isochoretic (n \u003d ¥);

4. Adiabatic (n \u003d g; where g \u003d c p / c V is an adiabatic coefficient).

The obtained ratios are valid for perfect gas and are a consequence of its equation of state, and the considered processes are private and limiting manifestations of real processes. The real processes are usually intermediate, proceed with arbitrary values \u200b\u200bof "N" and obtained the name of polytropic processes.

If you compare the work of the expansion of the perfect gas produced in the thermodynamic processes considered, with a change in volume from V 1 to V 2, then, as can be seen from fig. 5.2, the greatest expansion work is performed in the isobaric process, smaller - in isothermal and even less - in adiabatic. For a isohorotic process, the work is zero.

Fig. 5.2. P \u003d F (v) -dependence for various thermodynamic processes (shaded areas characterize the operation of the expansion in the appropriate process)

Transport Energy (Core Transport) Air humidity. Heat capacity and air enthalpy

Air humidity. Heat capacity and air enthalpy

The atmospheric air is a mixture of dry air and water vapor (from 0.2% to 2.6%). Thus, the air can almost always be viewed as wet.

Mechanical mixture of dry air with water vapor is called wet air or air-steam mixture. The maximum possible content of vapor moisture in the air m P.N. Depends on temperature t. and pressure P. Mixtures. When it changes t. and P. The air can move from the originally unsatisted in the saturation state with water vapors, and then the excessive moisture will begin to fall out in the gas volume and on the fencing surfaces in the form of fog, ina or snow.

The main parameters characterizing the condition of wet air are: temperature, pressure, specific volume, moisture content, absolute and relative humidity, molecular weight, gas constant, heat capacity and enthalpy.

By the Dalton Law for Gas Mixtures full pressure of wet air (p) There is the sum of partial pressures of dry air P C and water vapor p p: p \u003d p c + r.

Similarly, volume V and mass M wet air will be determined by the ratios:

V \u003d V C + V P, M \u003d M C + M p.

Density and specific volume of wet air (V) Determined:

Molecular weight of wet air:

where B is barometric pressure.

Since during drying, the air humidity continuously increases, and the amount of dry air in the steam-air mixture remains constant, then the drying process is judged by how the amount of water vapor per 1 kg of dry air is changing, and all the indicators of the steam-air mixture (heat capacity, moisture content, enthalpy and Dr.)) refer to 1 kg of dry air in wet air.

d \u003d m n / m C, g / kg, or, x \u003d m p / m c.

Absolute humidity- Course weight in 1 m 3 wet air. This value is numerically equal.

Relative humidity -this is the ratio of the absolute humidity of unsaturated air to the absolute humidity of saturated air under the given conditions:

here, but more often the relative humidity is asked as a percentage.

For wet air density, the ratio is true:

Specific heat Wet air:

c \u003d C + C P × D / 1000 \u003d C + C P × X, KJ / (kg × ° C),

where with C is the specific heat of dry air, with C \u003d 1.0;

with P - specific steam capacity; with n \u003d 1.8.

The heat capacity of dry air at constant pressure and small temperature ranges (up to 100 ° C) for approximate calculations can be considered a constant equal to 1.0048 kJ / (kg × ° C). For superheated steam, the average isobaric heat capacity at atmospheric pressure and low detection of overheating can also be made constant and equal to 1.96 kJ / (kg × K).

Entalpy (I) Wet Air - This is one of its main parameters, which is widely used in the calculations of the drying plants mainly to determine the heat consumed on the evaporation of moisture from the drying materials. Enhalar air enthalpy refer to one kilogram of dry air in the steam-air mixture and is determined as an amount of dry air enthalpy and water vapor, that is

i \u003d i c + i p × x, kj / kg.

When calculating the enthalpy of mixtures, the initial point of the enthalpium of each component should be the same. For calculations of wet air, it can be assumed that the enthalpy of water is zero at 0 ° C, then the enthalpy of dry air also count from 0 ° C, that is, I \u003d C * T \u003d 1.0048T.

TEMPERATURE . It is measured both in Kelvink (K) and in degrees Celsius (° C). The size of the degree Celsius and the size of Kelvin is the same for the difference in temperatures. The ratio between temperatures:

t \u003d T - 273,15 K,

where t. - temperature, ° С, T. - Temperature, K.

PRESSURE . Pressure of wet air p. and its components is measured in PA (Pascal) and multiple units (KPA, GPA, MPa).
Barometric Waste Air Pressure p B. equal to the amount of dura air partial pressures p B. and water vapor p P. :

p b \u003d p in + p n

DENSITY . Waste air density ρ , kg / m3, is the ratio of the mass of the air-steam mixture to the volume of this mixture:

ρ \u003d m / v \u003d m in / v + m n / v

Wet air density can be determined by the formula

ρ \u003d 3.488 p b / t - 1.32 p n / t

SPECIFIC GRAVITY . Spelled wet air γ - This is the ratio of weight of wet air to the volume occupied by it, N / m 3. Density and share related addiction

ρ \u003d γ / g,

where g. - Acceleration of free incidence, equal to 9.81 m / s 2.

AIR HUMIDITY . The content in the air of the water vapor. It is characterized by two values: absolute and relative humidity.
Absolute air humidity. The amount of water vapor, kg or g contained in 1 m 3 of air.
Relative air humidity φ , expressed in%. The ratio of the partial pressure of the water vapor PP contained in the air to the partial pressure of the water vapor in the air with its full saturation of water vapors P of P.N. :

φ \u003d (p n / p P.N.) 100%

Partial water vapor pressure in saturated wet air can be determined from expression

lG P P.N. \u003d 2,125 + (156 + 8,12t V.N.) / (236 + T V.N.),

where t V.N. - Saturated wet air temperature, ° C.

DEW POINT . Temperature at which partial pressure of water vapor p P. contained in wet air equal to partial pressure of saturated water vapor p P.N. at the same temperature. At the dew temperature begins condensation of moisture from the air.

d \u003d m p / m in

d \u003d 622p n / (p b - p n) \u003d 6,22φp P.N. (P b - φp P.N. / 100)

SPECIFIC HEAT . The specific heat capacity of wet air C, KJ / (kg * ° C) is the amount of heat required for heating 1 kg of a mixture of dry air and water vapor to 10 and referred to 1 kg of dry part of the air:

c \u003d C B + C P D / 1000,

where c B. - the average specific heat capacity of dry air, received in the temperature range of 0-1000s equal to 1.005 kJ / (kg * ° C); With P is the average specific heat capacity of a water vapor equal to 1.8 kJ / (kg * ° C). For practical calculations in the design of heating systems, ventilation and air conditioning, it is allowed to use the specific heat capacity of wet air C \u003d 1.0056 kJ / (kg * ° C) (at 0 ° C and barometric pressure 1013.3 GPa)

Specific enthalpy . Specific enthalpy of wet air is enthalpy I., KJ, assigned to 1 kg of dry air mass:

I \u003d 1,005t + (2500 + 1.8068t) D / 1000,
or i \u003d ct + 2.5d

Volume expansion coefficient . Temperature Coefficient of Volume Expansion

α \u003d 0.00367 ° C -1
or α \u003d 1/273 ° C -1.

Parameters of the mixture .
Temperature of air mixture

t cm \u003d (M 1 T 1 + m 2 T 2) / (M 1 + m 2)

d cm \u003d (m 1 d 1 + m 2 d 2) / (M 1 + m 2)

Specific enthalpy of air mixture

I cm \u003d (m 1 i 1 + m 2 i 2) / (m 1 + m 2)

where M 1, M 2 - Masses of mixed air

Filter classes

Application	Cleaning class					Cleaning degree
	Standards	DIN 24185. DIN 24184.	EN 779.	Eurovent 4/5	EN 1882.
Filter for coarse cleaning with low air purity requirements	Rough Cleaning	EU1	G1.	EU1	—	A%
The filter used at a high concentration of dust with rough cleaning from it, air conditioning and exhaust agency with low requirements for indoor air purity.						65
		EU2.	G2.	EU2.	—	80
		EU3.	G3.	EU3.	—	90
		EU4.	G4.	EU4.	—
Separation of fine dust in ventilation equipment used in rooms with high air splices. Filter for very thin filtration. The second sehes of cleaning (fingering) in rooms with average air purity requirements.	Thin cleaning	EU5	EU5	EU5	—	E%
						60
		EU6.	EU6.	EU6.	—	80
		EU7.	EU7.	EU7.	—	90
		EU8.	EU8.	EU8.	—	95
		EU9	EU9	EU9	—
Cleaning from superflux dust. It is used in premises with increased air purity requirements ("clean room"). Finishing air purification into the premises of precision equipment, surgical blocks, resuscitation chambers, in the pharmaceutical industry.	Especially thin cleaning	—	—	—	EU5	FROM%
						97
		—	—	—	EU6.	99
		—	—	—	EU7.	99,99
		—	—	—	EU8.	99,999

Calculation of calorfor power

Heated, ° С
m 3 / h	5	10	15	20	25	30	35	40	45	50
100	0.2	0.3	0.5	0.7	0.8	1.0	1.2	1.4	1.5	1.7
200	0.3	0.7	1.0	1.4	1.7	2.0	2.4	2.7	3.0	3.4
300	0.5	1.0	1.5	2.0	2.5	3.0	3.6	4.1	4.6	5.1
400	0.7	1.4	2.0	2.7	3.4	4.1	4.7	5.4	6.1	6.8
500	0.8	1.7	2.5	3.4	4.2	5.1	5.9	6.8	7.6	8.5
600	1.0	2.0	3.0	4.1	5.1	6.1	7.1	8.1	9.1	10.1
700	1.2	2.4	3.6	4.7	5.9	7.1	8.3	9.5	10.7	11.8
800	1.4	2.7	4.1	5.4	6.8	8.1	9.5	10.8	12.2	13.5
900	1.5	3.0	4.6	6.1	7.6	9.1	10.7	12.2	13.7	15.2
1000	1.7	3.4	5.1	6.8	8.5	10.1	11.8	13.5	15.2	16.9
1100	1.9	3.7	5.6	7.4	9.3	11.2	13.0	14.9	16.7	18.6
1200	2.0	4.1	6.1	8.1	10.1	12.2	14.2	16.2	18.3	20.3
1300	2.2	4.4	6.6	8.8	11.0	13.2	15.4	17.6	19.8	22.0
1400	2.4	4.7	7.1	9.5	11.8	14.2	16.6	18.9	21.3	23.7
1500	2.5	5.1	7.6	10.1	12.7	15.2	17.8	20.3	22.8	25.4
1600	2.7	5.4	8.1	10.8	13.5	16.2	18.9	21.6	24.3	27.1
1700	2.9	5.7	8.6	11.5	14.4	17.2	20.1	23.0	25.9	28.7
1800	3.0	6.1	9.1	12.2	15.2	18.3	21.3	24.3	27.4	30.4
1900	3.2	6.4	9.6	12.8	16.1	19.3	22.5	25.7	28.9	32.1
2000	3.4	6.8	10.1	13.5	16.9	20.3	23.7	27.1	30.4	33.8

Standards and regulatory documents

SNiP 2.01.01-82 - Construction climatology and geophysics

Information on climatic conditions of specific territories.

SNiP 2.04.05-91 * - heating, ventilation and air conditioning

These construction regulations should be observed in the design of heating, ventilation and air conditioning in the premises of buildings and structures (hereinafter - buildings). When designing, it is also necessary to comply with the requirements for heating, ventilation and air conditioning SNIP of the respective buildings and premises, as well as departmental standards and other regulatory documents approved and agreed with the Russian State Building.

Snip 2.01.02-85 * - Fireproof standards

These standards must be respected in the development of projects of buildings and structures.

These norms establish the fire and technical classification of buildings and structures, their elements, building structures, materials, as well as general fire protection requirements for constructive and planning decisions of premises, buildings and structures of various purposes.

These norms are complemented and refined by fireproof requirements outlined in SNiP of part 2 and in other regulatory documents approved or agreed by the Gosstroke.

SNIP II-3-79 * - construction heat engineering

Real standards of construction heat engineers should be observed in the design of enclosing structures (external and interior walls, partitions, coatings, attic and interchaltering floors, floors, fillings of openings: windows, lamps, doors, gates) of new and reconstructed buildings and structures of various purposes (residential, public , industrial and auxiliary industrial enterprises, agricultural and warehouse, with normalized temperatures or temperature and relative humidity of internal air).

SNIP II-12-77 - noise protection

These norms and rules should be respected in the design of noise protection to ensure admissible levels of sound pressure and sound levels in premises in workplaces in industrial and auxiliary buildings and at the fields of industrial enterprises, in premises of residential and public buildings, as well as in the residential territory of cities and other settlements.

SNIP 2.08.01-89 * - residential buildings

These norms and rules apply to the design of residential buildings (apartment buildings, including apartment buildings for elderly and families with disabled people moving on wheelchairs, in the future text. Families with disabled families, as well as hostels) up to 25 floors inclusive.

These norms and rules do not apply to the design of inventory and mobile buildings.

SNIP 2.08.02-89 * - Public buildings and structures

These norms and rules apply to the design of public buildings (up to 16 floors inclusive) and structures, as well as public premises embedded in residential buildings. When designing public premises built into residential buildings, SNIP 2.08.01-89 * (residential buildings) should be additionally guided.

SNIP 2.09.04-87 * - Administrative and household buildings

These norms apply to the design of administrative and domestic buildings up to 16 floors inclusive and premises of enterprises. These norms do not apply to the design of administrative buildings and public premises.

When designing buildings tunable due to the expansion, reconstruction or technical re-equipment of enterprises, retreat from these standards in terms of geometric parameters is allowed.

SNiP 2.09.02-85 * - Production buildings

These norms apply to the design of industrial buildings and premises. These norms do not apply to the design of buildings and premises for the production and storage of explosives and explosion means, underground and mobile (inventory) buildings.

Snip 111-28-75 - Rules for production and acceptance of work

Starting tests of mounted ventilation and air conditioning systems are carried out in accordance with the requirements of SNIP 111-28-75 "Rules of production and acceptance of work" after the mechanical testing of the ventilation and related energy equipment. The purpose of starting tests and adjustment of ventilation and air conditioning systems is to establish the compliance of the parameters of their operation to project and regulatory.

Prior to the start of testing, the installation of ventilation and air conditioning should be continuously and properly worked for 7 hours.

When starting trials must be manufactured:

• Checking the conformity of the settings for installed equipment and elements of the ventilation devices adopted in the project, as well as the compliance of the quality of their manufacture and install the requirements of TU and SNiP.
• Detection of looseness in air ducts and other elements of systems
• Checking compliance with project data of volumetric costs of air passing through air-actuate and air distribution devices of general ventilation and air conditioning equipment
• Checking compliance with passport data of ventilation equipment on performance and pressure
• Checking the uniformity of heating calorificates. (In the absence of a coolant in the warm period of the year, checking the uniformity of the heating of the calorifers is not produced)

Table of physical quantities

Fundamental constants
Permanent (number) Avogadro	N A.	6.0221367 (36) * 10 23 mol -1
Universal gas constant	R.	8.314510 (70) J / (mol * k)
Permanent Boltzmanna	k \u003d r / na	1.380658 (12) * 10 -23 J / K
Absolute zero temperature	0k.	-273.150C.
Speed \u200b\u200bspeed in the air under normal conditions		331.4 m / s
Acceleration of gravity	g.	9.80665 m / s 2
Length (m)
micron	μ (μm)	1 μm \u003d 10 -6 m \u003d 10 -3 cm
angstrom	-	1 - \u003d 0.1 nm \u003d 10-10 m
yard	yd.	0.9144 m \u003d 91.44 cm
foot	Ft.	0.3048 m \u003d 30.48 cm
inch	IN.	0.0254 m \u003d 2.54 cm
Area, m2)
Square yard	YD 2.	0.8361 m 2.
Square foot	FT 2.	0.0929 m 2.
square inch	in 2.	6.4516 cm 2.
Volume, m3)
Cubic yard	YD 3.	0.7645 m 3.
cubic foot	FT 3.	28.3168 DM 3.
cubic inch	In 3.	16.3871 cm 3.
Gallon (English)	GAL (UK)	4.5461 DM 3.
Gallon (USA)	GAL (US)	3.7854 DM 3.
Pinta (English)	Pt (UK)	0.5683 DM 3.
Dry Pint (USA)	DRY PT (US)	0.5506 DM 3.
Liquid Pint (USA)	Liq Pt (US)	0.4732 DM 3.
Liquid oz (English)	FL.OZ (UK)	29.5737 cm 3.
Liquid oz (USA)	FL.OZ (US)	29.5737 cm 3.
Bushel (USA)	BU (US)	35.2393 DM 3.
Dry barrel (USA)	BBL (US)	115.628 DM 3.
Mass (kg)
lb.	LB.	0.4536 kg
Slag	Slug.	14.5939 kg
grandfather	GR.	64.7989 MG.
Trading ounce	Oz.	28.3495
Density (kg / m 3)
pound on cubic foot	LB / FT 3	16.0185 kg / m 3
pound on cubic inch	LB / IN 3	27680 kg / m 3
Cubic foot	SLUG / FT 3	515.4 kg / m 3
Thermodynamic temperature (K)
Degree Renkina	° R.	5/9 K.
Temperature (K)
Degree Fahrenheit	° F.	5/9 k; T ° C \u003d 5/9 * (T ° F - 32)
Power, weight (H or kg * m / c 2)
Newton	N.	1 kg * m / c 2
Powl	PDL	0.1383 H.
pound-power	lbf.	4.4482 H.
kilogram-power	KGF.	9.807 H.
Specific weight (n / m 3)
pound power on cubic inch	LBF / FT 3	157.087 H / m 3
Pressure (Pa or kg / (m * C 2) or N / m 2)
pascal	PA	1 N / m 2
hectopascal	GPa	10 2 PA
Kilopascal	Kpa	10 3 PA
bar	Bar	10 5 N / m 2
Physical atmosphere	ATM	1.013 * 10 5 N / m 2
Millimeter mercury pillar	MM HG.	1.333 * 10 2 N / m 2
Kilogram-force on cubic centimeter	KGF / CM 3	9.807 * 10 4 N / m 2
Powl on square foot	PDL / FT 2	1.4882 N / m 2
pound power per square foot	LBF / FT 2	47.8803 N / m 2
pound power per square inch	LBF / IN 2	6894.76 N / m 2
foot of water column	ft h 2 o	2989.07 N / m 2
inch water column	in h 2 o	249.089 N / m 2
inch mercury pillar	in hg.	3386.39 N / m 2
Work, energy, heat (J or kg * m 2 / c 2 or n * m)
joule	J.	1 kg * m 2 / c 2 \u003d 1 n * m
calorie	Cal.	4.187 J.
Cylolaria	KCAL	4187 J.
Kilowatt-hour	kwh.	3.6 * 10 6 J
British thermal unit	BTU.	1055.06 J.
foot-pahundal	ft * pdl	0.0421 J.
foot-pound	ft * lbf.	1.3558 J.
liter-atmosphere	L * ATM	101.328 J.
Power, W)
Foot Poundal per second	ft * pdl / s	0.0421 W.
Foot-pound power per second	ft * lbf / s	1.3558 W.
Horsepower (English)	HP.	745.7 W.
British thermal unit per hour	BTU / H.	0.2931 W.
kilogram-power-meter per second	KGF * M / S	9.807 W.
Mass flow (kg / s)
pound mass per second	LBM / S.	0.4536 kg / s
Thermal conductivity coefficient (W / (M * K))
British thermal unit for a second-foot-degree Fahrenheit	BTU / (S * ft * degf)	6230.64 W / (M * K)
Coefficient of heat transfer (W / (m 2 * k))
British thermal unit for a second - square foot-degree Fahrenheit	BTU / (S * ft 2 * degf)	20441.7 W / (m 2 * k)
Temperature coefficient, kinematic viscosity (m 2 / s)
Stokes.	ST (ST)	10 -4 m 2 / s
Santistoks	CST (CST)	10 -6 m 2 / s \u003d 1mm 2 / s
Square ft for a second	ft 2 / s	0.0929 m 2 / s
Dynamic viscosity (PA * C)
PUAZ	P (P)	0.1 PA * with
Santipuise CP.	(SP)	10 6 PA * with
Poundal Second on Square Foot	PDT * S / FT 2	1.488 Pa * with
Pound Second Power per square foot	LBF * S / FT 2	47.88 PA * with
Specific heat (J / (kg * k))
calorie on gram-degree Celsius	CAL / (G * ° C)	4.1868 * 10 3 J / (kg * k)
British thermal unit for pound-degree Fahrenheit	BTU / (LB * DeGF)	4187 J / (kg * k)
Specific entropy (J / (kg * k))
British thermal unit for pound degrees Renkina	BTU / (LB * DEGR)	4187 J / (kg * k)
The density of the heat flux (W / m 2)
Cylolaria per meter square - hour	KCAL / (M 2 * H)	1.163 W / m 2
British thermal unit per square foot - hour	BTU / (FT 2 * H)	3.157 W / m 2
Moisture permeability of building structures
kilogram per hour per meter millimeter water column	KG / (H * M * mm H 2 O)	28.3255 mg (C * M * PA)
Volume permeability of building structures
Cubic meter per hour per meter-millimeter water column	M 3 / (H * M * mm H 2 O)	28.3255 * 10 -6 m 2 / (C * PA)
The power of light
Kandela	CD	The main unit of S.
Illumination (LC)
lux	LK	1 cd * cp / m 2 (cp - steradian)
photo	pH (photos)	10 4 LK
Brightness (CD / m 2)
Styb.	ST (ST)	10 4 kD / m 2
NIT	NT (NT)	1 cd / m 2

Group of Companies Inresol

Which is necessary to change the temperature of the working fluid, in this case, air, one degree. The heat capacity of the air directly depends on temperature and pressure. At the same time, various methods can be used to study different types of heat capacity.

Mathematically, air heat capacity is expressed as the ratio of the amount of heat to the increment of its temperature. The heat capacity of the body having a mass of 1 kg is customary to be called specific. The molar heat capacity of air is the heat capacity of one praying matter. Designated heat capacity - J / K. Molar heat capacity, respectively, J / (mol * K).

The heat capacity can be considered a physical characteristic of any substance, in this case of air, if the measurement is carried out under constant conditions. Most often, such measurements are carried out at constant pressure. This is how the isobaric heat capacity of air is determined. It increases with an increase in temperature and pressure, and is also a linear function of these values. In this case, the temperature change occurs at constant pressure. To calculate the isobaric heat capacity, it is necessary to determine the pseudocritic temperature and pressure. It is determined using reference data.

Air heat capacity. Features

Air is a gas mixture. When consideration, the following assumptions were taken in thermodynamics. Each gas in the composition of the mixture should be evenly distributed throughout the volume. Thus, the volume of gas is equal to the volume of the whole mixture. Each gas in the composition of the mixture has its partial pressure, which it renders on the walls of the vessel. Each of the components of the gas mixture should have a temperature equal to the temperature of the entire mixture. In this case, the sum of partial pressures of all components is equal to the pressure of the mixture. The calculation of air heat capacity is carried out on the basis of data on the composition of the gas mixture and the heat capacity of individual components.

The heat capacity ambiguously characterizes the substance. Of the first law of thermodynamics, it can be concluded that the internal energy of the body varies not only depending on the amount of heat obtained, but also from the perfect body of work. Under different conditions of the heat transfer process, the body work may vary. Thus, the same reported body is the amount of heat, can cause various in the meaning of temperature change and internal body energy. This feature is characteristic only for gaseous substances. Unlike solid and liquid bodies, gaseous substances can strongly change the volume and work. That is why the heat capacity of air defines the nature of the thermodynamic process itself.

However, with a constant volume, the air does not work. Therefore, the change in internal energy is proportional to the change in its temperature. The ratio of heat capacity in a constant pressure process, to heat capacity in the process with a constant volume is part of the formula of the adiabatic process. It is indicated by the Gampea Gamma Literary.

From the history

The terms "heat capacity" and "the amount of heat" do not well describe their essence. This is due to the fact that they came into modern science from the theory of heator plant, which was popular in the eighteenth century. The followers of this theory were considered warmth as a kind of weightless substance, which is contained in bodies. This substance cannot be destroyed or created. Cooling and heating of bodies were explained by a decrease in or increasing the heat vehicle content, respectively. Over time, this theory was invalid. She could not explain why the same change in the internal energy of any body is obtained by transmitting it a different amount of warmth, and also depends on the body performed by the body.