Weak current College】 【Central air conditioning & refrigeration industry nomenclature resolved (1) --- 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. The refrigeration of commonly used terms describe briefly as follows: <br .> <br> 1.1 temperature <br> <br> 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. 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> 1.2 thermal <br> <br> Body temperature of a substance that the body heat, and sports drastic temperature of said objects with 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. Commonly used heat units are: a. card in 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. joules <br> <br> 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. 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. Our statutory thermal unit is the Joule. <br> <br> Joule and card .conversion: <br> <br> 1kJ (thousand joules) = 0.239kcaI (kcal) <br> <br> Lkcal (kcal) = 4.19kJ (thousand joules) <br> <br> Other common conversion formula is: <br .> <br> 1kcal (kcal) = 3.969Btu (yingre units) <br> <br> LBtu (yingre units) = 252cal (card) <br> <br> 1kcal (kcal) = 427kg · m (kg · m) .<br> <br> 1kW (kW) = 860kca1 / h (kcal / h) <br> <br> 1 United States ton = 3024kca1 / h (kcal / h) <br> <br> 1 Japan ton = 3320kca1 / .h (kcal / h) <br> <br> 1.3 specific heat <br> <br> 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. <br> <br> Several materials than the calorific value of < .br> <br> Material name specific heat kJ (kg · K) supplies the name of the specific heat kJ (kg · K) <br> <br> Ammonia water 4.19 (liquid) 4.609 <br> <br> Ice 2.095 2.179 .ammonia (gas) <br> <br> Glass 0.754 1.006 air (stem) <br> <br> Copper 0.390 <br> <br> Steel 0.461 <br> <br> Know the material 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: <br> <br> M: water quality, kg; c: specific heat of water kJ (kg · K); Dt: temperature difference K. <br> <br> 1.4 sensible heat <br> <br> For .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 <br> <br> 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 pointThe 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 and 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 < .br> <br> Gas composition by molecular, hundreds of 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. <br> <br> 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. <br> <br> 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: <br> <br> Absolute pressure = local atmospheric pressure to 10 work <br> < .br> Only absolute pressure is the psychrometric parameter. <br> <br> B £ ® water vapour partial pressure and the saturated water vapour partial pressure <br> <br> 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. <br> <br> 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. <br> <br> That is, P = Pq Pg 10 <br> <br> Or B = Pq Pg 10 <br> <br> In the .air conditioning in the humid air is moist air atmosphere, so the total pressure P is B local atmospheric pressure. <br> <br> 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. <br> <br> 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 845 ° c. In the refrigeration system, used to control the pressure to achieve control of evaporation evaporation temperature. <br> <br>.