This standard specifies the main terms and their meanings used in refrigeration equipment. JB/T 7249-1994 Refrigeration Equipment Terminology JB/T7249-1994 Standard download decompression password: www.bzxz.net

1 Subject Content
Machinery Industry Standard of the People's Republic of China
Terms of Refrigeration Equipment
This standard specifies the main terms used in refrigeration equipment and their meanings. 2 General Terms
2.1 Refrigeration
The process of extracting heat from a space or object below the ambient temperature and transferring it to the ambient medium. 2.2 Refrigerating Machine Refrigerating Machine JB/T 7249-94
The whole of machinery and equipment connected in sequence according to the refrigeration cycle, including the prime mover. These machinery and equipment are in contact with the refrigerant.
2.3 Refrigerating Machinery Refrigerating Machinery A general term for various types of refrigerators and refrigeration equipment. It usually refers to a refrigeration system composed of part or all of the following machines and equipment: compressor, condenser, generator, absorber, liquid receiver, throttling mechanism, connecting pipes and evaporator, etc. 2.4 Refrigerating Plant Refrigerating plant and cold-consuming equipment as a whole, including all accessories, control equipment, cold-consuming equipment and enclosure structure. They are usually in contact with refrigerants and coolants.
2. 5 Refrigerating EngineeringRefrigerating EngineeringThe design, manufacture, application and operation of refrigerators and their main equipment. 2.6 Cryogenics
The technology and science of producing temperatures below -120℃ to absolute zero. 2.7 Compression-type refrigerating machineCompression-type refrigerating machineA refrigerator in which the compressor completes the compression process. 2.8 Absorption-type refrigerating machineA refrigerator composed of absorber, generator, evaporator, condenser, etc. 2. 9 Steam-jet refrigerating machineSteam-jet refrigerating machineA refrigerator that produces cold by vaporizing a fluid by using a high-pressure steam ejector to generate a pressure drop. 2.10 Heat-pumpHeat-pump
A refrigeration system used to transfer heat to a certain space or object. At this time, the evaporator absorbs heat from the outdoor air, water, etc., and the condenser releases heat to heat a certain space or object. If the flow direction of the refrigerant is changed, the heat pump system can also be used to cool a certain space or object. 2.11 Heating heat pump A refrigeration system that mainly uses the system's own heat rejection to complete the heating function. 2.12 Cooling and heating heat pump A refrigeration system that absorbs heat from a low temperature and rejects heat to a high temperature. It can use the two functions of cooling and heating alternately or simultaneously. 2.13 Peltier effect When an electric current passes through the junction of two different metals or the connection of an alloy or semiconductor, the heat diffusion or heat absorption effect generated there Approved by the Ministry of Machinery Industry of the People's Republic of China on July 18, 1994 and implemented on July 1, 1995
JB/T 7249-94
2.14 Ranque-Hilsoh effect The cooling effect caused by the formation of vortices when the gas enters the tube from the tangential direction 2.15 Joule-Thomson effect The ratio of temperature change to pressure change in actual gas throttling or expansion without external work or heat exchange (dT/dforce). Thermo-electric refrigeration 2.16
A refrigeration method using the Peltier effect.
Semiconductor refrigeration A refrigeration method using the Peltier effect of semiconductors. 2.18 Vortex tube
Equipment for cooling using the Rank-Hull back effect. 2.19
Fluid
A general term for gases and liquids.
Laminar flow
Unperturbed flow between fluid particles.
Turbulent flow
Flow with disturbances between fluid particles, usually with many vortices. Density
Mass of a substance per unit volume.
Specific volume
The volume occupied by a unit mass of a substance. Viscosity
The property of a semi-liquid, liquid, or gas that prevents its shape or arrangement of parts from changing instantaneously. It is caused by the friction between fluids in relative motion.
Absolute viscosity
The force per unit area required to produce a unit relative velocity when two parallel surfaces of a fluid are separated by a unit distance. It is also called dynamic viscosity. 5 Kinematic viscosity 2.26
The ratio of the absolute viscosity of a fluid to its density.
Environment surroundings
The surroundings of a thermodynamic system.
Critical velocity critical velocity
·A flow velocity at which a certain phenomenon occurs. .
In fluid flow, above this velocity the fluid becomes turbulent flow. In nozzle flow, the velocity at which the fluid reaches the speed of sound in the nozzle. For nitrogen, the maximum velocity at which superfluidity can be maintained. d.
Calibration
The process of correcting the existing scale of an instrument scale or determining the error of the existing scale. 2.30
Demarcation
The process of marking or calibrating an instrument scale. 2.31 Machine room
A room where refrigeration equipment is installed and where workers are provided with operating facilities. 2.32
Declination of sun
The angle between the line connecting the center of the sun and the center of the earth and the equatorial plane of the earth. If it is above the equatorial plane (north), it is expressed as a positive value; if it is below the equatorial plane (south), it is expressed as a negative value. 2.33 Degree day
A unit of cumulative temperature reduction based on temperature difference and time. Used to estimate the fuel consumption of buildings during winter heating and to specify the rated heating load of buildings in winter. 2.34 Solar constant solar constant
The intensity of solar radiation on a plane perpendicular to the sun's rays outside the earth's atmosphere when the distance from the sun is equal to the average distance between the earth and the sun.
2.35 Standard atmospheric pressure normal atomospheric pressure An artificial atmospheric pressure value used for calculations. The value of standard atmospheric pressure is usually set at 101.325 kPa. 2.36 Wiredrawing
The flushing effect caused by the high-speed flow of fluid through the valve plug or valve seat. Usually caused by delayed action in the state close to closing. In the suction process of reciprocating refrigeration compressors, it causes suction pressure loss. 2.37 Thermal insulation thermal insulation measures to reduce heat transfer using materials or structures with high thermal resistance. 2.38 Sound insulation sound insulation
Acoustic treatment to isolate the machine housing, air inlet pipe, other parts of the system and equipment and the surrounding of the room from sound transmission and vibration transmission. 2.39
Noise reduction
Measures to absorb sound energy or reduce sound intensity 2.40 Accumulation of cold "cold" stored in the form of sensible heat (i.e. lowering the temperature of a substance) or latent heat (freezing a liquid or solution). 3 Thermodynamic and heat transfer terms
Phase change
The transition between the three states of matter (solid, liquid, gas). Fog
Liquid droplets suspended in a gas
3.3Frost
When the air temperature is below 0℃, the water vapor contained in it freezes into ice and snow. Liquefaction
The state change of gas into liquid.
Evaporation
The state change of liquid into vapor.
Melting
The state change of solid into liquid.
Sweating
The process of water vapor in the air condensing into water droplets on the surface below the dew point temperature. Lyophilization
The drying technology of freezing the water contained in the substance and then sublimating the ice. Thermodynamic parameters3.9
The basic quantities used to describe the state of matter. For example, temperature, pressure, specific volume, melting point, etc. 3.10 Boiling point
The temperature at the liquid-vapor interface when the vapor pressure of the liquid vapor is equal to the external absolute pressure. 3.11 Melting point
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The temperature at which the solid and liquid phases of a substance are in equilibrium at a given pressure. 3.12 Dew point
The temperature at which water vapor in a gas mixture begins to condense when the temperature is lowered. 3.13 Critical point A state point of a substance. At this point, liquid and vapor have exactly the same physical parameters. Critical temperature (criticaltemperature), critical pressure (critical pressure) and critical specific volume (critical volume) refer to the temperature, pressure and specific volume of the critical point respectively.
internal energy
3.14 Internal energy
The sum of the molecular kinetic energy and molecular potential energy contained in a substance. It includes the molecular kinetic energy, the vibration energy of atoms and electrons, and the molecular potential energy formed to overcome the intermolecular forces. 3.15 Latent heat of vaporization (condensation) The difference in phase transition between gas and liquid. 3.16 Heat of fusion
The latent heat of phase transition between solid and liquid. Heat of reaction
The amount of heat absorbed or released per unit mass (or mole) of reactants or products during a chemical reaction. 3.18 Ideal gas
An idealized gas that complies with the pV=RT relationship.
3.19 Actual gas
Any gas or vapor that actually exists (different from an ideal gas). 3.20 Gas constant The constant R in the ideal gas state equation pV=RT. 3.21 Compressibility factor The correction factor added when the ideal gas state equation is used to represent the actual gas state relationship. Usually the compressibility factor Z is expressed as pV/RT.
isolated system
In thermodynamics, a system that has no exchange of mass or energy with its environment. 3.23 boundary conditionsboundary conditionsThe physical conditions imposed on a system at the boundary separating it from its environment (e.g. the value of a physical quantity, the conditions for energy exchange, etc.). 3.24 thermal equilibriumthermal equilibriumThe equilibrium reached by a system when the temperature is uniform. 3.25
transient state
The transitional state of a system from one state to another. 3.26 steady state
The state in which the physical quantities at each point in a system with mass exchange and energy conversion do not change with time. 7 unsteady state
The state in which the physical quantities at any point in a system change with timeEnthalpy
A thermodynamic property of a substance, defined as the sum of its internal energy and a value V. where is the pressure of the substance and V is its volume. 9 specific enthalpy
per unit mass of a substance.
3.30 entropy
ratio of the heat introduced into a thermodynamic system to the absolute temperature of the thermodynamic system. 74
3.31 specific entropy
per unit mass of a substance.
3.32 exergy
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the portion of energy that can be converted into the maximum useful work. '3.33
specific exergy
per unit mass of a substance.
anergy
the portion of energy that cannot be converted into technical work. Available energy
the energy of the total energy of an ideal engine that can be converted into work. Mollier diagram
a diagram showing the properties of a refrigerant. Usually uses melting point and entropy as coordinates. Also used to represent the properties of moist air, with flame and moisture content as coordinates (used in air conditioning).
pressure-melt diagram (ph diagram) pressure enthalpy chart A thermodynamic state diagram of a substance using pressure and h as coordinates. 3.38
enthalpy entropy chart A thermodynamic state diagram of a substance using melting point and entropy as coordinates. Temperature entropy chart (T-diagram) temperature entropy chart3.39wwW.bzxz.Net
A thermodynamic state diagram of a substance using temperature and entropy as coordinates. 3.40 psychrometric chart A diagram representing the thermodynamic properties of moist air. Usually uses entropy and moisture content as coordinates, from which the temperature, moisture content, relative entropy, relative humidity and water vapor partial pressure of moist air at a given pressure can be found. 3.41
pressure-volume diagram (pV diagram) pressure volume diagram A thermodynamic state diagram of a substance using pressure as the ordinate and volume V as the abscissa. saturated vapor
Vapor in which the gaseous and liquid phases are in equilibrium. 3.43dry-saturated vapordry-saturated vaporVapor at a temperature corresponding to the saturation pressure and without any suspended liquid. 3.44superheated vaporsuperheated vapor
Vapor at a temperature higher than the saturation temperature corresponding to the pressure. 3.45quality
The mass percentage of vapor in a mixture of liquid and vapor. 3.46dry air
Air without moisture. 3.47humidity ratio
The mass of water vapor in wet air that coexists with dry air (in grams). 3.48humidity
The amount of water vapor in wet air, representing the degree of dryness or wetness of the air. 3.49
Absolute humidityabsolute humidity
The mass of water vapor in unit volume of wet air under standard conditions (0℃, 10'Pa). 3.50
Relative humidityrelative humidity
The ratio of the partial pressure of water vapor in wet air to the partial pressure of saturated water vapor at the same temperature. Expressed as a percentage. 3.511
Critical pressureoritical pressure
JB/T 7249-—94
The vapor pressure corresponding to the critical state of a substance. In the critical state, liquid and vapor have exactly the same physical parameters. Saturation pressuresaturation pressure3.52
At any given temperature, the saturation pressure of a pure substance is equal to the pressure at which vapor and liquid or liquid and solid can coexist in a stable equilibrium. Suction pressuresuction pressure
The working pressure in the refrigeration system measured in the suction line at the compressor inlet. 3.54
Discharge pressure
The working pressure in the refrigeration system measured in the discharge line at the compressor outlet. 3.55
Design working pressureThe pressure used to determine the calculated thickness or mechanical strength of each component when designing a specific part of a refrigeration system. 3.56 Operating pressureWhen the refrigeration system is operating normally. The pressure at a certain point in the system indicated by the pressure gauge. 3.57
Low pressure side
The part of the refrigeration system where the pressure is roughly equal to the evaporation pressure. High pressure side
The part of the refrigeration system where the pressure is roughly equal to the condensation pressure. 3.59 Pressure ratio
The ratio of the pressures at two specific points in the refrigeration system. 3.60 Pressure drop
The pressure loss caused by friction, throttling, etc. when the fluid flows. 3.61
Pressure equalizingThe pressure on the high and low pressure sides tends to be equal during shutdown to reduce the starting torque of the compressor. Isothermal process
Thermodynamic process with constant temperature.
adiabatic process
thermodynamic process in which the system does not exchange heat with the outside world. polytropic process
a process in which the state of a gas changes as represented by the equation "plus\=constant". In the equation, force is pressure, V is specific volume, and n is the polytropic index. 3.65
throttling
an irreversible adiabatic process in which a fluid expands and reduces pressure through an orifice without doing external work. expansion
the phenomenon of an increase in the volume of a substance.
adiabatic expansion
expansion in which a fluid does not exchange heat with the outside world. polytropic expansion in which a fluid has the ability to exchange heat.
isenthalpic expansion in which there is no exchange of heat or mechanical energy with the outside world and the value remains constant. multistage expansion3.70
expansion of a refrigerant flowing through two or more expansion valves in series. 3.71
Expansion Linerc-expansion Line
On the dynamometer diagram, it represents the pressure change curve of the gas in the clearance volume before the suction valve opens during the piston return stroke as the cylinder volume increases.
compression
3.72Compression
The process of increasing the pressure of gaseous refrigerant.
adiabatic compressionadiabatic compressionJB/T 7249-94
Compression of gas without heat exchange with the environment. 3.74
polytropic compressionCompression in which the gas exchanges heat with the outside and the gas temperature changes during the process. 3.75
wet compressionwet compression
Compression in a refrigeration system in which the vapor sucked into the compressor is mixed with liquid refrigerant, causing the compressor's exhaust to be saturated vapor instead of superheated vapor.
3.76 compression exponent The exponent n in the equation "\constant" during compression is called the compression exponent, which represents the relationship between the pressure and specific volume during compression.
3.77 single-stage compression The compression from evaporation pressure to condensation pressure is completed in only one stage. 3.78 multistage compression Two or more stages of compression. Usually two or more stages of compression in which the discharge port of one compressor is connected to the suction port of another compressor, or staged compression in different cylinders of a compressor. 3.79 subcaoling
The process of reducing the temperature of a gaseous or liquid refrigerant to below the saturation temperature at a given pressure. 3. 80 degree of subcooling The difference between the saturation temperature and the subcooling temperature of a refrigerant at the same condensing pressure in a refrigeration cycle. 3.81
superheat
The state in which the temperature of the refrigerant vapor is higher than the saturation temperature at a given pressure. 3.82
degree of superheat
The difference between the superheat temperature and the saturation temperature of the refrigerant at the same evaporating pressure in the refrigeration cycle. chilling
The process of lowering the temperature of an object by removing heat above the freezing point. intercooling
The cooling of the refrigerant between two compression stages by heat exchange between the cooling medium and the refrigerant. 3.85
condensation
The process of converting vapor into liquid by removing heat. preheating
The heating of food before subsequent processing.
The heating of air in an air conditioning system before other processes. 3.87 precooling
The cooling of refrigerated goods before transportation. Precooling of materials in refrigeration and chemical processes before the main temperature reduction. 3.881
Flash gas
Gas generated by the sudden vaporization of a portion of a liquid refrigerant due to a sudden decrease in pressure. 3.89
Noncondensable gas Gas that does not liquefy at the condensing temperature in a refrigeration system. Corrosion inhibitor
An additive added to brine or absorbent liquid to reduce or prevent corrosion. 3.91Antifreeze agent
JB/T 7249—94
A substance added to a liquid to reduce its freezing point. 2Moisture content
The mass of water contained in a unit mass of a substance. 3Gauge pressure
The pressure value that exceeds the atmospheric pressure.
Static pressure
The pressure of a fluid at rest or the force measured perpendicular to the fluid flow line. velocity pressure
The pressure in excess of the static pressure caused by the conversion of kinetic energy into pressure energy when a fluid is stopped by an obstacle. 3.96
Total pressure
The sum of static and dynamic pressures.
Partial pressure
The pressure of a single component in a gas or vapor mixture. Vacuum
The state in which the pressure of a gas is lower than atmospheric pressure. Evacuation
The use of a vacuum pump or refrigerator to reduce the pressure in a system to a state lower than atmospheric pressure. 3.100 Aspiration
The movement of another fluid caused by the velocity of a fluid. Velocity head
In a moving fluid, the height of the fluid column itself or the height of the liquid column equal to the velocity pressure of the pressure fluid. Concentration
The percentage of a component in the total amount of a mixture. 3.103 Solubility
The amount of dissolved substance (solute) contained in a unit saturated solution at a given temperature and pressure. 3.104 Solvent
A substance that can dissolve other substances.
3.105 Solute
A substance that dissolves in another substance.
Absorption
The process by which a substance penetrates into another substance. 3.107 Adsorption
The process by which a solid absorbs another fluid by surface adhesion. 3.108 Decomposition
A chemical change process that breaks down the structure of a substance, such as the decomposition of water into oxygen and hydrogen. 3.109 Hydrolysis
Decomposition of a compound by chemical reaction with water. Diffusion
Molecular movement of two substances or parts of the same substance with different densities in a closed volume toward a uniform concentration or density due to a concentration difference or density difference.
3.111 Mass diffusivity The ratio of the mass flow of a substance diffusing through a unit surface area to the rate of change of the concentration of the substance perpendicular to this surface. 3.112 Flame ability
The burning ability of a material.
3.113 Heat transfer
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The process of heat transfer from one substance to another. Mass transfer
The process of transferring a single component in a mixture. Thermal radiation
The process of transmitting energy outward in the form of electromagnetic radiation caused by temperature. When any wavelength of radiation energy is absorbed by an object, it is converted into heat energy, causing the temperature of the absorbing object to rise. 3.116 Thermal conduction The process of heat transfer through solid matter. 3.117 Emissivity
The ratio of the radiation power of a radiator to that of a black body (an ideal object that absorbs all radiation energy) at the same temperature. 3.118
Absorptance
The ratio of the radiation energy absorbed by a surface to the radiation energy projected onto the surface from the outside. 3.119 Transmittance
The ratio of the energy that penetrates an object to the energy projected onto the object from the outside. 3.120 Reflectance
The ratio of the reflected energy of an object to the radiation energy projected onto the object from the outside. 3.121 Direct solar radiation intensity The solar radiation energy per unit area on the plane perpendicular to the sun's rays on the earth's surface. diffuse solar radiation3.122
Radiation from the sun that comes down from the sky and is refracted and reflected by clouds. 3.123
3 convection
A form of heat transfer that relies on the motion of a fluid. 3.124 free thermal convectionA form of heat transfer that relies on the motion of parts of a fluid due to density differences caused by temperature changes. 3.125 forced thermal convectionA form of heat transfer that relies on mechanically induced fluid motion. 3.126 parallel flow
The flow of two fluids in the same direction in a heat exchanger. 3.127 counter flow
The flow of two fluids in opposite directions in a heat exchanger that are roughly parallel. 3.128 crash-flow
The flow of two fluids in a heat exchanger that are perpendicular to each other. 3.129heat transfer coefficientthermal transmittanceThe amount of heat transferred per unit time, per unit temperature difference, and per unit area when the fluids on both sides of the heat transfer body are in a steady state. 3.130heat transfer film coefficientThe amount of heat transferred per unit area and per unit time under a unit temperature difference between the surface and the fluid during stable heat exchange. 3.131thermal conductivityThe amount of heat flowing through a homogeneous material per unit area and per unit thickness per unit time under a steady state of maintaining a unit temperature gradient in a direction perpendicular to the material area.
3.132fin efficiencyfin efficiency
The ratio of the actual heat transfer of the fin to the heat transfer assuming that the temperature of the entire fin surface is the temperature of the fin root. 79
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