An Investigation On Frost Restraint For Air Source Heat Pump By Using Indoor Exhaust Air Energy

Air source heat pump system is an efficient energy utilization technology, for it can absorb low grade energy from ambient air and transport these energy to consumer. In actually, the frosting of outdoor heat exchanger is a big obstacle for the extension of air source heat pump: for one thing, the frosting reduced the performance of outdoor heat exchanger, and it is dangerous for frequently open-stop operations to defrost the frost on the surface of outdoor heat exchanger; for another thing, the defrosting process should stop supply heat to consumer, or even absorbing heat from consumer, reducing the comfortable of consumer.To restrain the frosting process of air source heat pump, a method by using indoor exhaust air energy is proposed, the mixture air, ie the ambient air mixed with the indoor exhaust air, is dehumidified by a solid dehumidification apparatus, and then exchange heat with the outdoor heat exchanger. On the one hand, it can recycle the energy of indoor exhaust air. On the other hand, it can restraint the frosting process, even for realizing the frost free operation of air source heat pump.Frost restraint of air source heat pump by using indoor exhaust air energy can be reflected in two aspects: reducing the chance of frosting and restraining the severity of frosting. To study the effects of indoor exhaust air energy for restraining the frosting process of air source heat pump, theory and experimental methods are used, and the specific works are as follows:1) The theory frost areas of air source heat pump by using indoor exhaust air energy are achieved by theory calculation, and reducing the chance of frosting at different cities are analyzed on the base of meteorological data, and the applicability of indoor exhaust air energy at these cities are evaluated;2) The numerical model of air source heat pump by using indoor exhaust air energy is established with some hypotheses. And the parameters of frost quality, heating capacity and COP of air source heat pump by using indoor exhaust air energy can be calculated;3) An experimental study is conducted in the enthalpy difference test set-up, to experimental study the air source heat pump by using indoor exhaust air energy.4) The test result and numerical calculation result are compared. The results indicated that there is a certain distinction between them in the initial stage, for the respects of experimental system stability and hypothesis of numerical model, and they are similar since the stable stage;5) The application effect for the frosting process of air source heat pump restrained by indoor exhaust air energy are analyzed at different work conditions on the basis of test results.