10.翻译：翻译：
1. V apor compression compression refrigeration refrigeration refrigeration system system system is is is compod compod compod by by by compressor compressor ，condenr ，expansion expansion valve valve valve and and evaporator ，connected with pipe line to form an enclod system. Refrigerant changes heat with substance to
be be cooled cooled cooled in in in evaporator. evaporator. Refrigerator Refrigerator absorbs absorbs absorbs heat heat heat from from from substance substance substance to to to be be be cooled cooled cooled and and and evaporated. evaporated. evaporated. The The
compressor draws the low pressure vapor in its suction side and then compresd it to high pressure before discharge.
2. During During the the the cycle, cycle, cycle, compressor, compressor, compressor, which which which is is is heart heart heart of of of the the the system, system, system, plays plays plays a a a part part part in in in compressing compressing compressing and and and transporting transporting
refrigerant vapor and causing low pressure in evaporator and high pressure in condenr. Flow control valve throttles throttles refrigerant refrigerant refrigerant flow flow flow to to to reduce reduce reduce its its its pressure pressure pressure and and and regulates regulates regulates refrigerant refrigerant refrigerant flow flow flow rate rate rate of of of entering entering entering evaporator. evaporator.
Evaporator, which is an equipment of refrigerating effect output, refrigerant absorbs heat form substance to be cooled to realize refrigerating. Condenr, which is an equipment of heat output, coolant in it takes away heat from refrigerant and heat from the work consumed by compressor.
3. In liquid evaporating refrigerating systems, refrigerant is required to evaporate at low temperature. It absorbs
heat heat from from from objects objects objects to to to be be be cooled. cooled. cooled. Then Then Then condens condens condens at at at higher higher higher temperature temperature temperature and and and discharges discharges discharges heat heat heat to to to environment environment
meanwhile. Therefore, only tho evaporate and conden within range of working temperature can be ud as refrigerants. Most refrigerants are in gaous state at normal temperature and pressure.
4. Mixed Mixed refrigerant refrigerant refrigerant is is is compod compod compod by by by two two two kinds kinds kinds or or or more more more pure pure pure refrigerants. refrigerants. refrigerants. Due Due Due to to to limitation limitation limitation to to to type type type and and
performance of pure refrigerants, mixture of refrigerant offers more freedom to modulate performance and
amplify choice of refrigerant.
9翻译翻译
1. 1. Boiler Boiler Boiler is is is a a a kind kind kind of of of heat heat heat exchange exchange exchange device device device which which which turns turns turns chemical chemical chemical energy energy energy and and and excess excess excess heat heat heat from from from industrial industrial
production process or other heat source into steam or hot water with certain temperature and pressure. 社保转出
2. 2. According According According to to to heat heat heat transfer transfer transfer features features features of of of boiler, boiler, boiler, industrial industrial industrial boiler boiler boiler heat heat heat surface surface surface can can can be be be divided divided divided into into into radiant radiant radiant heat heat
surface and convection heat surface. Radiant heat surface is that portion of surface of being located in combustion chamber and receive radiant heat. Manly means water cooled wall. Convection heat surface, located in boiler flue, is that portion of surface swashed directly by high temperature flue gas to transfer heat by convection.
3. 3. Boiler Boiler Boiler heat heat heat efficiency efficiency efficiency is is is an an an important important important technique technique technique index index index of of of boiler. boiler. boiler. Boiler Boiler Boiler heat heat heat efficiency efficiency efficiency means means means when when when boiler boiler
operating with rating load, how many percent of the heat from fully burning of fuel nt into b
oiler per hour to produce steam or hot water.
4. Boiler has broad applications and various types. Some common criteria ud in classifying them are: structure of boiler, application of boiler, fuel or energy ud by boiler, type of combusting, ventilation mode, circulation mode and arrangement of boiler drum
8 翻译翻译
1. 1. HV HV AC AC means means means to to to realize realize realize regulating regulating regulating and and and controlling controlling controlling of of of temperature, temperature, temperature, humidity, humidity, humidity, cleanliness cleanliness cleanliness and and and air air air velocity velocity velocity for for certain certain room room room or or or space, space, space, providing providing providing adequate adequate adequate fresh fresh fresh air air air meantime. meantime. meantime. HV HV AC AC is is is called called called Air Air Air conditioning conditioning conditioning for for for short. short. short. Air Air
conditioning can realize overall controlling to heat and humidity environment and air quality in buildings, or to say it contains partial function of heating and ventilation.
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2. 2. All All All -air -air -air system system system is is a a system system system that that that cooling cooling cooling or or or heating heating heating load load load in in in room room room is is is undertaken completely undertaken completely by by air. air. air. An An all-air
system supplies nsible heat cooling capacity and latent heat cooling capacity by delivering cold air into room. Process Process of of of cooling cooling cooling down down down and and and dehumidification dehumidification dehumidification of of of air air air are are are accomplished accomplished accomplished by by by air air air handling handling handling unit unit unit which which which locates locates
completely completely in in in air air air conditioning conditioning conditioning machine machine machine room. room. room. Supplemental Supplemental Supplemental cooling cooling cooling in in in room room room is is is no no no more more more required, required, required, yet yet yet heat heat heat of of
supply air can be achieved either in air conditioning machine room or in individual room. Air treatment for all-air system is mainly centralized in air conditioning machine room, so it is commonly called central air conditioning system.
3. Air -water system is a system that cooling or heating load in room is undertaken by both air and water. Besides supplying treated fresh air to room, terminal unit with circulation media of water installed in room heats and cools indoor air.
7 翻译翻译
1. Ventilation is main approach to ensure indoor air quality. That is, displacing indoor air of higher contaminant concentration concentration with with with outdoor outdoor outdoor air air air of of of much much much lower lower lower contaminant contaminant contaminant concentration. concentration. concentration. V V entilation rate rate needed needed needed should should should be be
determined determined by by by principle principle principle of of of diluting diluting diluting indoor indoor indoor contaminant contaminant contaminant to to to reach reach reach concentration concentration concentration specified specified specified by by by standard. standard. standard. Main Main
contaminant contaminant source source source is is is people people people in in in people people people occupied occupied occupied buildings. buildings. buildings. So So So the the th
e requisite requisite requisite ventilation ventilation ventilation rate rate rate ––fresh fresh air air air rate rate rate is is
ascertained by people. That is, fresh air rate is ascertained by diluting carbon dioxide relead by people. In order to to take take take into into into account account account diluting diluting diluting other other other contaminant contaminant contaminant and and and odor odor odor aroud aroud aroud by by by people people people’’s s activity activity activity at at at the the the same same same time, time, time, many many
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countries control carbon dioxide at 0.1%, while suggestion value of WHO is 0.25%.
2. Air condition buildings are commonly well airtight. If no reasonable exists, indoor air quality in it is not better than than common common common building building building with with with well well well ventilating. ventilating. ventilating. V entilation V entilation issues issues issues are are are accomplished accomplished accomplished by by by air air air conditioning conditioning conditioning system system
except special treatment for hazardous gas relead by technique process in air conditioning buildings. Special fresh air system is installed in air-water system to supply fresh
air to individual room to fulfill task of ventilation and improve air quality. Outdoor fresh air should be introduced into all-air system and mixed with return air, and then the mixture is delivered to room to dilute indoor contaminant after been treated.
3. Local air exhaust is a kind of local ventilation which removes contaminant directly from contaminant source. When When contaminant contaminant contaminant occurs occurs occurs centrally centrally centrally in in in somewhere, somewhere, somewhere, local local local air air air exhaust exhaust exhaust is is the the most most most effective effective effective way way way to to to treat treat treat harm harm harm of of
contaminant to environment. If overall ventilation is adopted in such situation, contaminant may spread in rooms. When contaminant occurs in large amount, ventilation volume needed to dilute it can be too much to realize in practice. Local air exhaust system consists of exhaust hood 、fan 、air cleaner 、air ducts 、exhaust outlet.
4. 4. Nature Nature Nature ventilation ventilation ventilation caud caud caud by by by heat heat heat pressure pressure pressure or or or wind wind wind pressure pressure pressure is is is widely widely widely ud ud ud ventilation. ventilation. ventilation. Common Common Common residential residential
building, office building, industrial workshop depend on nature ventilation to ensure indoor air quality. Otherwi,
natural ventilation is a kind of ventilation which is difficult to be controlled effectively. Only by understanding its basic principle and taking certain measure can we get nature ventilation going on according to out pret mode. 5. Ventilation rate is always lf-balanced practically when a room is ventilated. Air balance we referred to here means designing balance in the light of willing of designer or occupier. If balance designed has not performed, ventilation requirements may not be satisfied when system practically operates in balanced state. For example, a t of local exhaust system is installed to eliminate contaminant emitted by contaminant source in room. But the system doesn ’t work well when operating and ventilation rate does n’n’t reach the need. The problem lies in that the t reach the need. The problem lies in that the
腌制白萝卜room is in bament and has good air permeability performance. Meanwhile, abnce of air intake system and passage gives ri to higher negative pressure and reduces ventilation rate of air exhaust system.
七色花童话故事6 翻译翻译
1. nature gas is generally divided into four kinds: gas exploited from gas well of gas field is called pure natural gas or gas of gas well; gas exploited accompanying with petroleum is called petroleum gas or petroleum accompanied gas; gas which has light fraction of petroleum is called condensate gas of gas field; gas drawn from coal bed of coal well is called coal mine well gas. 如何补气血
2. Density variation should be taken into account when computing gas flow in pipes. Density of gas reduces with declining of pressure along the pipe line. Only in low pressure pipes the change in density of gas can be omitted.
3. 3. For For For the the the sake sake sake of of of making making making distribution distribution distribution system system system with with with very very very high high high economical economical economical index, index, index, optimal optimal optimal gas gas gas pipeline pipeline pipeline route route route is is
lected and number of gas pressure regulating room and distribution center is determined besides correct choice of of pipe pipe pipe diameter. diameter. diameter. There There There are are are generally generally generally many many many kinds kinds kinds of of of design
design design schemes schemes schemes to to to be be be encountered encountered encountered during during during the the the process process process of of
designing, therefore an optimal scheme should be picked out from them.
5 翻译翻译
1. 1. Heating Heating Heating by by by convection convection convection which which which is is is major major major type type type of of of heat heat heat transfer transfer transfer is is is called called called convection convection convection heating. heating. Heat Heat emitting emitting
equipment in the system is radiator, so this kind of system is also called radiator heating system. It supplies heat to room room by by by heat heat heat convection. convection. convection. Radiant Radiant Radiant heating heating heating is is a a kind kind kind of heating of heating type type mainly mainly mainly by by by radiant radiant heat heat transfer. transfer. transfer. Main Main Main heat heat
emitting equipment of radiant heating system is metal radiant panel or part of ceiling 、floor 、wall of building as radiant surface.
2. C irculating system can be divided into gravity circulating system and forced circulating system according to circulating power. System System circulating by water density difference is called gravity circulating system. circulating by water density difference is called gravity circulating system.
System circulating by mechanical force is called gravity circulating system. The force of gravity heating system depends on change of water temperature of the loop
3. 3. There There There are are are many many many factors factors factors influence influence influence heat heat heat transfer transfer transfer coefficient coefficient coefficient of of of radiator: radiator: radiator: manufacture manufacture manufacture condition condition condition of of of radiator radiator
(material, geometric dimension, structure form, spray coating of surface etc.) and application condition of radiator (media, temperature, flow rate, indoor air temperature and velocity, fitting type and combined piece etc.). They all synthetically influence heat emitting performance of radiator.
4 翻译翻译
1．Main issue of fluid dynamics is space distribution of velocity and pressure, velocity is more important between the two, inertia force and viscous force have clo relationship with velocity. In the two forces, inertia force occurs with with velocity velocity velocity variation variation variation of of of mass mass mass point point point itlf itlf itlf while while while viscous viscous viscous force force force is is is caud caud caud by by by velocity velocity velocity difference difference difference between between between flow flow layers and mass points.
2. Law of variation of viscosity coefficient with temperature is different between water and air. Viscosity of water reduces with increasing of temperature while increas for air. This is becau viscosity is result of attractive force between articles and irregular thermal motion to arou momentum exchange of articles. When temperature ris, attractive attractive force force force between between between articles articles articles decreas decreas decreas and and and momentum momentum momentum increas. increas. increas. Converly, Converly, Converly, when when when temperature temperature temperature decreas, decreas, attractive force between articles increas and momentum decreas. 2020人口普查
3. Heat transfer caud by density difference and gravity is called natural convection. Heat tra
nsfer coefficient of natural convection is generally lower than that of forced convection, therefore, when computing total heat gain or heat loss, the main point is radiant heat should not be ignored. Radiant heat transfer and natural convection may have have the the the same same same order order order of of of magnitude magnitude magnitude even even even under under under indoor indoor indoor temperature temperature temperature conditions, conditions, conditions, becau becau becau indoor indoor indoor wall wall wall temperature temperature affects comfortable nsation of human body.
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1. Heat conduction is thought as heat transfers from high temperature zone to low temperature zone in object by gradually energy exchange with particles of substance. During the conduction, there is no specific displacement of articles. But for mental, motion of free electrons is greatly helpful to heat conduction.
2. Fluid directly connected with the surface is heated and becomes less-den by heat conduction and moves upwards due to density difference with adjacent fluid. This motion is hindered by viscosity of fluid. The heat transmission is affected by the following factors ：
（1）gravity caud by heat expansion ；（2）viscosity （3）heat diffusion
This heat transmission is regard as depending on acceleration of gravity 、coefficient of thermal expansion 、
coefficient of motion viscosity and coefficient of thermal conductivity.
3. As for surface with different geometric shape, radiant characteristic and direction, when heat transfer rate is evaluated, assumptions are: (1) all surfaces are gray or black; (2) radiation or reflective diffu reflection; (3) the whole surface parameters are homogeneous . (4) emissivity is equal to absorptivity and has no relationship with temperature of project source. (5) objects between two radiant surfaces neither emit nor absorb radiation. The assumptions assumptions are are are ud ud ud due due due to to to providing providing providing simplification simplification simplification to to large large content, content, content, although although although the the the results results results are are are only only only thought thought thought as as approximate.
2 翻译翻译
1. Energy transfers between system and environment under temperature difference is called heat. Heat transfer of system and environment stops when system and environment are in thermal equilibrium. Once heat enters system through boundary, it turns into a part of system storage energy, that is, internal energy. It is obvious that heat is process factor relevant to process, while internal energy is state factor depending on thermodynamic state.
关系代词有哪些2. T he Carnot cycle and Carnot theorem have important theoretical and impractical meaning in the rearch of thermodynamics. It provides upper limits on efficiency of heat engine and theoretically propos the approach to increa efficiency. The efficiency of other impractical cycle is always less than the efficiency of the Carnot
cycle operating between the same two rervoirs.
3. The meaning of the increa of entropy principle
：(1) estimate the direction of a process by the increa of entropy principle of an isolated system
；（2）the increa of entropy principle can rve as judgment of system equilibrium-when entropy of an isolated system reaches maximum value
，system is under equilibrium state. （3）
the increa of entropy principle has clo relationship with the irreversibility of a process. The more irreversible
，
the more increa of entropy. So it is ud to evaluate perfect of thermodynamical performance of a process
