Air conditioning and hot water compound system in which air-cooling heat exchanger is connected with heat recovery heat exchanger in series is studied, system fundamentals and five running modes including single refrigerating mode, single heating mode, hot water mode, refrigerating and hot water mode and heating and hot water mode are introduced, and experimental research is developed. Experimental research on operation characteristics of refrigerating capacity, heating capacity and suction and discharge temperature and pressure show that the unit operates reliably long in different operation conditions and that the variation of characteristics is within a reasonable range. Coefficient of performance of the system in refrigerating and hot water mode and in heating and hot water mode is highest with the minimal value approximately 3.2 when the temperature of water tank climbs up to 55°C, as the service efficiency of the unit is improved by recovering the condenser heat to heat hot water. The system is avoided to operate in the region of maximum power, and had better operate in the variable flow region of capillary and large air volume and small temperature difference region as much as possible.

A new type of water-water multi-functional system consisting of double four-way valve is studied. System fundamentals and the operation modes are introduced. Experimental research on operation characteristics of refrigerating capacity, heating capacity, suction and discharge temperature and pressure shows that the unit operates reliably long in different operation conditions, and that the variation of characteristics is within a reasonable range. Coefficient of performance of the unit in refrigerating and hot water mode is highest and EER reaches up to 5.2 with the minimal value approximately 4, as the service efficiency of the unit is improved by recovering the condenser heat to heat hot water.

The performance of double-source heat pump water heater in different season realizes the different functions is analyzed through experiment,and the questions which appeared to the system is answered.The research indicated that this double-source heat pump operating condition is good,the stable property is highly effective,it may enhanced the energy synthesis efficiency effectively,and raised the equipment utilization rate effectively.

An experiment is carried out on the R417a used in air resource heat pump water heater under different hot water temperature under 7℃ operating mode.The discharge pressure,power input and Coefficient of Performance(COP) of the R417a are analyzed compared to R22.The result shows that the discharge pressure,compressor power input is lower than the R22 when mixed working substance R417a,the thermal power is reliable being effected by the temperature of hot water,the cop of the R417a drops rapidly,but its average cop is slightly higher than the R22 system.

Using coaxial pipe heat exchanger as heat recovery components,the operating performance on air source heat pump water heater with cylic heating was studied.Based on the experiment results,with water tank temperature ranging from 15℃to 55℃,the system parameters such as inlet,exhaust pressure,inlet and outlet water temperature rose,the coefficient of performance was about 3.69 and showed the feasibility of this system.