TechnicallyRefrigerationThat makes a system (i. E. Space or object)TemperatureIt is below the temperature of the surrounding environmental medium and sustains this low temperature process, which is referred to here as air and water from nature. Refrigeration andAir conditioningThe equipment uses fluids (the sum of gas and liquids) as the carrying energy material to effect the conversion or transfer of heat between thermal energy and other forms of energy (mainly mechanical). This chapter describes the nature of fluids, patterns of conversion between thermal and mechanical energy and patterns of heat transfer, which are essential theoretical foundations of air-conditioning technologies。
Work is in the refrigeration system, from gas to liquid and from liquid to gas, and this change in the state of the refrigerant, as well as temperature rises and drops, pressure changes, heat inhaling and heat release, are certainHeatologyInside relationships. A number of parameters, terminology and basic concepts are presented to prepare for the basics of thermodynamics. Temperature: is the parameter used to measure the coolness and heat of the object. The conversion relationship between temperature indicators for three units: °c (°c) fahrenheit (°f) absolute temperature (k) is: °c = 5/9 (°f – 32) °f = 9/5 °c + 32 k = °c + 273. 15. Dry ball temperature: the air temperature measured by a general thermometer is the true temperature of the air. Wet ball temperature: the temperature of the air is measured by a wet cotton veil in the area of the wet ball thermometer, which is called the wet ball temperature when the heat passed to water is exactly the same as that required for the evaporation of the water surface, as the water in the cotton veil is intended to absorb the heat of the air at the time of evaporation. Dry-wet ball temperature differentials: the dry-wet-ball thermometer shows a higher temperature when measuring unsaturated air, the wet-ball thermometer shows a lower temperature and two temperature differentials are called "dry-wet-ball differentials". The temperature difference is large, which means that the air is dry; the temperature difference is small, which means that the air is wet. I'm sorry.Humidity: humidity represents the amount of water vapour in air. Water vapour weights per kilogram of air are referred to as wetness in grams/kg. The humidity is divided into absolute and relative humidity. Absolute humidity is the weight of water vapour per cubic metre of light air and the weight of water vapour at its sub-pressure and wet air temperature in kg/m3. Relative humidity is the ratio of absolute humidity of wet air to absolute humidity in saturation, with a percentage. Dry air when the relative humidity is 0% and saturated vapour when the relative humidity is 100%. The relative humidity of human comfort is 60-70%. Episode temperature: the temperature of the wet air is reduced by cooling to the temperature of the water vapour contained in the air at the beginning of condensation (i. E. Reaching full saturation). Pressure (physics called pressure): engineering refers to the vertical force of the unit area as pressure. The international units are pa (pa), kpa (kpa), mpa (mpa), and the former units of engineering were kg/cm2 (kgf/cm2) and bar. 1mpa = 10. 2 kgf/cm2 = 7500. 6 mmhg (mm mercury column) = 100 mh2 o (meta-water mercury) = 10bar absolute pressure = surface pressure + atmospheric pressure vacuity = atmospheric pressure - absolute pressure 7. Thermal: is a measure of thermal energy transfer of the substance. The units are jj, kj, used in the past (cal), kcal. Their conversion relationship is 1 cal = 4. 18 j. 8. The heat absorbed or released at 1°c when the temperature of the substance is higher or lower than 1 kg. Symbol c, kj/kg degree (kj/kg k). 9. Heat: when the object is heated or cooled, only temperature changes occur without changes in state, and the heat it absorbs or releases. Potential heat: the substance changes its state and keeps its temperature constant during heating or cooling, when the heat it absorbs or releases. Evaporation: vapourization of liquid surfaces. Liquids can evaporate at various temperatures. Boiling: the liquid surface and interior are also subject to intense carbureting. The liquid will boil at a certain boiling point temperature at a certain pressure. 12. Condensation: the phenomenon of liquidization of gases into liquids. Two processes of cooling and condensing. 13. Ratio: volume occupied by substances in weight. In m3/kg (m3/kg). 14. Density: substances in volume, weight. In kg/m3 (kg/m3). Internal energy: internal energy is the sum of kinetic and inner energy of gaseous molecules. Dynamic energy is the sum of molecular motion energy, and inner energy is the energy that comes from the attraction of molecules. Engineering often uses 1kg mass as the subject of the study, so internal energy is commonly referred to as the energy of 1kg mass. 16. External: moleculars maintain their original approximation and the energy to confront the outside. 17. Validity: it is an ability. The energy required to move objects with external force is the power. Unit: n. M., formerly kg. M. Gw = distance moved in the direction of exterior forces x forces. Power: validation in unit time. Units: wa (w), kilowatt (kw). Overheating: saturated vapours continue to be heated above saturated temperatures, known as “overheated” gases, and the difference between the temperature and saturated temperature of excess gases is called overheat. Overcooled: saturated liquids continue to cool to below saturated temperatures called “overcooled” liquids under saturated pressure and the difference between the temperature and saturated temperature of the saturated liquids is called cold。
