WHAT IS A HEAT PUMP ?
Second law of thermodynamics states: ” The heat spontaneously moves from hotter bodies to bodies less heated .” Is it possible to force the heat to move in the opposite direction ? Yes, but in this case, additional costs of energy ( work) .
Systems which heat is transferred in the reverse direction is often called heat pumps. The heat pump can be a vapor compression refrigeration system , which consists of the following major components : compressor, condenser , expansion valve and evaporator. Gaseous refrigerant enters the compressor inlet . The compressor compresses the gas , with its pressure and temperature increase (universal gas law Mendeleev – Clapeyron ) . Hot gas is fed into the heat exchanger , called a condenser, where it is cooled , transferring its heat to water or air , and condenses – passes into a liquid state. Next, at high pressure fluid path set expansion valve reduces the pressure of the refrigerant. The compressor and the expansion valve closed hydraulic circuit divide into two parts: the high pressure side and the low pressure side . Passing through the expansion valve portion of the liquid evaporates and the temperature of the stream decreases.
Further, this stream enters the heat exchanger (evaporator ) associated with the environment (eg , air exchanger on the street) . At low pressure the liquid evaporates ( converted to gas ) at temperatures lower than the temperature of the outside air or the ground. As a result of the heat outside air enters the soil or to the internal energy of the refrigerant. Gaseous refrigerant is returned to the compressor – circuit closed.
We can say that the compressor is not so much on the “production” of heat , but on its movement . Therefore, wasting of 1 kW of electric power to drive the compressor , the condenser heat transfer can be about 5 kW. Heat pump easily get to work in the opposite direction, that is to use it to cool the room air in the summer.
Heating with heat pumps
Heating system based on the use of the heat pump , different environmental cleanliness , as they work without combustion and do not produce harmful emissions . Furthermore , they are characterized efficiency : when approaching the heat pump , for example , 1 kW of electricity depending on the operating mode and operating conditions it gives 3 – 5 kW of heat. Among the advantages of heat pump indicate a reduction in capital costs due to the lack of gas supply pipelines , increase home security due to the absence of flammable gas , the possibility of simultaneous production from one installation of heating, hot water and cooling systems .
Most heat pumps can operate in both heating and cooling.
Heating systems are monovalent and divalent . The difference between the two types is that the different environmental cleanliness have a heat source that completely covers the one-year heating demand . Bivalent systems are composed of two heat sources to extend the range of operating temperatures. For example, the heat pump operates until the outdoor temperature -25 ° C, and the temperature is decreased further in addition to connecting the gas or oil fired boiler to compensate for the reduction of the heat pump .
Heat pumps ZUBADAN Inverter
Mitsubishi Electric Corporation is a series system ZUBADAN Inverter ( in Japanese it means “super heating “). It is known that the performance of heat pumps for space heating using low-grade heat outdoor air decreases with temperature in the street. And this is a very significant reduction at the temperature of -20 ° C heat output up to 40% less than the nominal value specified in the specifications of instruments and measured at a temperature of +7 ° C. It is for this reason, air-source heat pumps do not consider our country as a full heater . Attitude towards them can change radically with the advent of heat pumps series ZUBADAN Inverter.