Weak current College】 【conditioning common terms --- Power By】 【China power house network.

<br> <br> Refrigeration is the mechanical method, from a limited number of spaces out heat, the temperature is reduced to the required extent. This process is accomplished by heat. <br> <br> The refrigeration of commonly used terms describe .briefly as follows: <br> <br> 1.1 temperature temperature are used for material cold and heat, and temperature of high and low level available thermometer to measure, such as glass thermometers, tube liquid heated expansion, contraction level elevated, cooling, liquid .surface to reduce the level of the liquid indicates the degree of high and low temperature. <br> <br> The following overview indicates the temperature value of several standards. <br> <br> A £ ® Celsius scales in standard atmospheric pressure, .the water of the freezing point as 0 degrees, boiling point as the 100 °, 0 ° c and 100 ° balanced between etch into 100 cells, each cell to l, symbol ° c degrees. <br> <br> B £ ® Fahrenheit .at standard atmospheric pressure, the freezing point of water at 32 degrees, and the boiling point is 212 degrees, between the balanced carved 180, each cell to l, a symbol oF representation. <br> <br> C £ ® the Kelvin temperature .scale (also known as the absolute temperature scale) it is based on the Celsius temperature scale, the freezing point of water as 273.16 degrees, water-boiling 373.16 degrees, in theory, the material elements of all stop motion as 0 degrees to symbol K .said. <br> <br> Common temperature scale is Celsius, Fahrenheit, Kelvin. <br> <br> The conversion formula is as follows: Fahrenheit Celsius Fahrenheit Celsius conversion: degrees Kelvin and Celsius: T = t + 273.16 type: T .: Kelvin scale, K; t: Celsius temperature scale, oC. <br> <br> 1.2 thermal object temperature level represents the object's material molecular thermal motion severe high or low temperature in degrees, also indicates that the object has the level of energy ., this energy is called heat. When the temperature difference of the two objects in contact, both the temperature gradually converge, the heat from the hot objects to temperature lower body shift, when the object is released or absorption of energy as heat. <br .> <br> Commonly used heat units are: <br> <br> A. card at standard atmospheric pressure, water will lg of heating or cooling, its temperature raised or lowered l ¡ .æ, the added or removed from the heat as l card symbol cal represents. Because the card unit is too small, often introduced the works 1000 times the kcal or kcal. A symbol for kcal. <br> <br> B. yingre units .in standard atmospheric pressure, 11b (lbs) (11b = 0.454kg) water heating or cooling, raise or lower the temperature in Fahrenheit loF, added to or removed from the heat as a unit, its symbol yingre as Btu. <br> < .br> C. j in the international system of units, taking heat units and power units to joules. Joule equivalent with 1N (Newton), a total of hot spot in the move in the direction of lm (m) work. <br> .<br> Therefore, in the international system of units, Joule is a unit of power and energy, this unit makes computing easier, the symbols for J j. <br> <br> Our statutory thermal unit is the Joule. Joule and card .conversion: 1kJ (thousand joules) = 0.239kcaI (kcal) lkcal (kcal) = 4.19kJ (thousand joules) other common conversion formula is: 1kcal (kcal) = 3.969Btu (yingre units) lBtu (yingre units) = 252cal (card .) 1kcal (kcal) = 427kg · m (kg · m) 1kW (kW) = 860kca1 / h (kcal / h) = 1 United States ton 3024kca1 / h (kcal / h) 1 Japan ton = 3320kca1 / h (kcal / .h) <br> <br> 1.3 specific heat of any substance when added calories, it's temperature will rise. But the same quality of different substances, elevated the same temperature, added calories is not the same. To each other, the water temperature .rises lkg 1 ° c the necessary heat for 4.19kJ. As standard, other substances required ratio of heat and it is called heat. If the water temperature rises lkg l ° c required calorific 4.19kJ, than to 4.19kJ (kg · ℃) ., lkg copper temperature l ¡ .æ simply 0.39kJ, copper heat to 0.39kJ (kg · ℃). Different materials have their own than calorific value, the following table for several materials than the calorific value. Several materials than the calorific value of the specific heat of material name kJ .(kg · K) supplies the name of the specific heat kJ (kg · K) water 4.19 ammonia (liquid) 4.609 ice 2.095 ammonia (gas) 2.179 glass 0.754 air (stem) 1.006 copper 0.390 steel 0.461 know materials than the caloric value, .you can calculate the required for it to cool down to remove heat. For example to the water cooling 5kg70 ° c to 15 ° c, you need to get rid of heat: Q = mcDt = 5 × 4.19 × (70-15) = .l152.25kJ type: m: water quality, kg; c: specific heat of water kJ (kg · K); Dt: temperature difference K. <br> <br> 1.4 sensible heat on solid, liquid or gaseous substances heating form as .long as it remains unchanged, the added heat, the temperature will rise of matter, how much of the added heat in temperature can be displayed, ie do not change the substance of the temperature changes caused by the heat as sensible heat. As for liquid .water to heat up, as long as it maintains the temperature of the liquid, it will rise; therefore, sensible heat only affects the temperature changes caused by the material's surface morphology changes. For example, the computer in the room or the heat exchanger is .large, it is sensible heat. <br> <br> 1.5 latent heat on liquid water heating, water temperature, when reached boiling point, although the heat is constantly, but the water temperature does not rise, remained in the boiling point, added .heat only the water into steam, that is, from liquid to gas. This does not change the substance of the change of temperature and physical state (also known as phase change) is called latent heat. Such as the computer room, staff body heat .toAnd ventilation with incoming air moisture content, the heat is called latent heat. (Total heat equal to sensible heat and latent heat.) <br> <br> 1.6 pressure gas from molecules to the millions of molecules in motion without rules, frequent crash .container wall, wall unit surface area on the vertical force known as the pressure generated by it. In engineering common measurement of gas pressure units: kg / cm 2, or as mmHg (mmHg), China's legal units is Pa (Pascal). A .. atmospheric pressure surrounding the Earth's air layer formation on the Earth surface area per unit of pressure is referred to as atmospheric pressure. Usually expressed with B. Units with PA Pa or kPa kPa. Atmospheric pressure varies throughout the altitude differences exist. Also because of .the season, climate change and slightly. As a result of atmospheric pressure, air of the physical nature and reflect the State of the physical properties of air parameters you want to change. Therefore, in the air-conditioned design and run, taking into account .the size of the local air pressure, otherwise it will cause some errors. Pressure points: determination of pressure used instruments (known as the pressure of work, ie table pressure), local atmospheric pressure and absolute pressure. Their mutual relationship: the absolute pressure .= local atmospheric pressure to 10 jobs is the only absolute pressure of moist air State parameters. B £ ® water vapour partial pressure and the saturated water vapour partial pressure in the humid air, steam alone possessed the wet air volume, and have the same temperature .and humid air produced by pressure, known as the water vapour partial pressure, Pq said. Moist air is dry air and steam composition of mixtures, the total pressure of moist air shall be determined by the partial pressure of dry air and water vapour of Pg .; partial pressure Pq superposition. That is, P = Pg 10 Pq or B = Pg 10 Pq in the air conditioning in the humid air is moist air atmosphere, so the total pressure P is B local atmospheric pressure. At a certain temperature, the .air is humid, the more water vapor content, the greater the partial pressure of water vapor. When the water vapor content exceeds a certain limit, the excess water vapor will congeal into water precipitated. This shows that, at this point, the water vapor .in the air and moisture content of maximum, the wet air saturation, known as saturated air; the corresponding partial pressure of water vapor is called saturation vapor pressure points. The pressure depends only on temperature, the higher the temperature, the pressure, the greater .the value. At the same time, the relationship between pressure and boiling points are also great, reduce the pressure to the boiling point of liquid, increased pressure is reduced so that the boiling point rise. Therefore each role in the liquid pressure has a boiling .point. For example, 1.0133 × l05Pa. Water boils at 100 ° c; If the pressure rise to 2.41 ¡ .á 105Pa, the boiling point of water is 138 ° c; if pressure is reduced to 0.43 ¡ .á 105Pa, the boiling point of water is 84.5 ℃. In the refrigeration system, used to control the pressure to achieve control of evaporation evaporation temperature. <br> <br> 1.7 evaporation and boiling evaporation refers to free-surface liquids gasification process. .For example, water evaporation. Clothes dry process. Evaporation on the surface of the liquid is due to the high energy of molecular overcome liquid molecules of gravitation, wear out liquid reaches of space. In the same environment, liquids, the higher the temperature, .the faster the evaporation. Refrigeration engineering, many issues are related to the evaporation process, such as cooling and humidification of air conditioning and drying process. Infrared humidifier humidification is surface evaporation process. Boiling is the liquid inside the bubble forms of violent gasification process. .For example, the process water to the boil. At a certain pressure, the liquid is heated to a certain temperature began to boil. Throughout the boiling process, liquid absorption of heat all for its volumetric expansion and the gas-liquid phase transition temperature remains .unchanged. If the electrode humidifiers belongs to the boiling process. <br> <br> 1.8 thermal conductivity (also known as thermal conductivity) thermal conductivity is a materials transfer heat capacity of a physical quantity. If two equally thick material, one is a .copper blocks, one is a cork blocks, put them in the high temperature than itself, you can feel the copper block temperature, and the Cork block you feel in a short time. This description of two materials on heat conduction of different capacities, the .materials on the thermal capacity of different transmission to digital representation is called thermal conductivity, its value is equal to: when the material layer thickness on both sides for the lm, the temperature difference of 1 ° c, the surface area of over lm2 1h the .conduction of heat, the symbol l, units are kcal / mh ℃, the State's legal units is W / mK or use J / mhK indicated that conversion between them is: 1W/mK = 0.860kcal/mh ℃. Different materials have different thermal .conductivity, and material composition, density, molecular structure, and other factors. The same kind of material, the thermal conductivity of the main factors is the density and moisture. Density, thermal conductivity, thermal conductivity of high humidity is also high. <br .> <br> 1.9 heat transfer coefficient when freezing of a substance, such as in surface blowing it freeze faster than not blowing time fast. Represents the different substances in different States heat capacity of the physical quantity known as the heat transfer coefficient, its value .is equal to the hourly, every square meters area, when fluid and solid wall for temperature-difference between l ° c the transfer of heat. To sign a representation, its units as kcal / (m2h ℃), the international system of units is .W / (m2k) or J / (m2h ℃), the relationship is between the two conversion: 1W / (m2K) = 0.860kcal / (m2h ° c) <br> <br> 1.10 heat transfer coefficient of heat from the hot .side of fluid through the flat wall transfer to low-temperature side fluid. This heat transfer capabilities in addition to temperature, heat transfer on both sides and the size of the area concerned, and the flat wall heat transmission coefficient, flat wall thickness of the .walls on either side of the heat transfer coefficient. All factors column into a single formula, namely: Q = KFDt (kJ / h) in the formula: Q: transmission of heat (kJ / h); F: flat wall surface area ( .m2); the temperature difference Dt: Dt = t1-t2 (° c); heat transfer coefficient K: kJ / (m2h ℃) K for numerical coefficient of heat transfer, it is equal to the temperature difference when the sides on l ° .c, heat transfer area by lm2 lh, thermal fluid from one side to another side of the cooling fluid transfer of heat. Unit is kJ / (m2h ° c) or W / (m2k). <br> <br> 1.11 specific volume .and density unitsVolume of moist air has the quality known as density. Represented by the symbol r, namely: the quality of the unit in humid air of a volume called the specific volume, use the symbol V said, namely: -: m: humid .air quality unit is kg; v: humid air of volume, m3. Both the countdown, therefore, can only be considered as a state parameter. <br> <br> 1.12 humidity humidity is humid air containing water vapor content in the number of .physical quantities, there are three types of representation. A £ ® absolute humidity lm3 wet air steam quality. Symbol for Z, unit is kg/m3, ie: -: mq: steam quality, kg; V: steam volume of possession, that .is, the wet air volume, expressed in m3. Absolute humidity is not convenient to use. It does not directly reflect the humid air of dry and wet. B. moisture content per kg dry air containing water vapor amount known as the moisture content, .symbols for d, unit is kg / kg (dry): type: mq: wet steam quality in air, the unit is kg; mg: wet air in the dry air mass, kg. B £ ® relative humidity and moisture in the air .and water vapour partial pressure and temperature of saturated water vapour partial pressure, known as relative humidity. J representation with symbols, namely: type: Pq: water vapour partial pressure Pqb; temperature with partial pressure of saturated steam from the type of the value j ., drier air, on the contrary, the air is relatively humid. When j = 0 to dry air; j = 100%, the air is saturated. From j-value size can directly see the extent of wet and dry air. J and .d is the air's humidity parameters, meaning but different, d content of water vapor, it cannot be said that the degree of air nearly saturated; j to represent the degree of air nearly saturated, but cannot express how much water vapor content. <br .> <br> 1.13 dew-point temperature at atmospheric pressure, moisture content does not change the steam condensation in the air to water (DEW) temperature. Unchanged at d, air temperature, from unsaturated State becomes saturated, air relative humidity j = 1O0 .per cent. In the air conditioning technology, the air temperature and dew point temperature, air dehumidification drying. <br> <br> 1.14 enthalpy enthalpy wet air is an important parameter. Is a bit with the pressure inside the can of composite state parameters .. In the air conditioning process, often moist air state changes, enthalpy can easily determine the status of the change in the amount of heat in the process. Humid air change process is the process of constant pressure, enthalpy difference equal to the heat capacity, .namely: tDh = DQ = cmDt-type: Dh: enthalpy difference kJ / kg (dry) DQ: heat capacity kJ / kgm: kgc moist air quality: humid air of the constant pressure heat kJ / (kg ¡ã c) <br .> <br> 1.15 static and dynamic pressure, full pressure in select air conditioning or fan, you often encounter the static and dynamic pressure, pressure these three concepts. According to the role of knowledge on fluid mechanics, fluid in the unit area is called .a vertical force on pressure. When the air flow along the wind pipe wall, the pressure can be divided into static and dynamic pressure and full pressure, unit is mmHg or kg/m2 or Pa, China's legal units is Pa. A. static pressure .(Pi) as the air molecules in irregular movement and impact on the tube wall is called static pressure. The calculation to calculate the absolute vacuum is called absolute zero of hydrostatic pressure. To atmospheric pressure to zero pressure is called relative static pressure. Air pressure .means relative static pressure. Static pressure above atmospheric pressure, is positive, lower than the atmospheric pressure is negative. B. dynamic pressure (Pb) means air flow pressure, as long as the wind tube air flow has certain dynamic pressure, its value is .always positive. C. full pressure (Pq) full pressure is static and dynamic pressure of algebra and: Pq = Pi x Pb full pressure represents lm3 gas with total energy. If the atmospheric starting point for the calculation, it can be positive, it .can be negative. <br> <br> <br> <br> <br> <br>.