Research On The Tecnology Improving The Adaptability Of ASHP Under Low Temperature Conditions

In recent years, more and more air source heat pumps(ASHP) are applied in the cold regions. But ASHP appear many problems and even can not work smoothly when the outdoor temperature becomes lower. For coping with these problems , there are many improvement methods, which are summed up in the study, and carry on a calculation to these methods under the same conditions, then analysis the outcomes, and make a comprehensive evaluation finally.There are mainly two improvement methods referred in this study, one is technique measures, which make the improvement in the components of the unit; the other one is improved system, which make the improvement in the circulation of the ASHP. The technique measures include adding electrical heater, enlarging the area of the outdoor heat exchanger, increasing the capacity of the compressor, increasing the temperature of the low temperature heat source and augmenting the air flow rate in the outdoor heat exchanger; the improved circulations include the single-stage ASHP with the liquid refrigerant injection to the compressor, quasi two-stage compression system, double-stage heat pump, and double-stage coupled heat pimp. First, these systems are calculated separately; second, use entropy weight analysis hierarchy process to evaluate the systems parameters from four aspects-security, heat capacity, power input and EER.These improved methods are compared, which is useful for the researchers and engineers in this field or other fields who want to choose reasonable schemes or evaluate heating systems. Additionally, the method used for evaluation which can be applied in the evaluation about the heat, ventilation and air conditioning systems and this method copes with the problems about the multiple criteria decision–making.