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• A new air conditioning system is explored by experiment. • The system starts mode H is the most stable, and the maximum superheat is 11°C. • A unique phenomenon occurs in the production of hot water. • The system fluctuates periodically in the refrigeration mode. • The drop in discharge pressure can be used as a parameter for defrost control. Air source heat pump (ASHP) and heat pump water heater (HPWH) have the advantages of convenience and high efficiency. The newly proposed refrigeration, heating and hot water combined air-conditioning system (RHHAC) combines traditional ASHP with HPWH. The demands of users for cooling, heating and hot water are effectively satisfied with this equipment. In this study, five groups of experiments were conducted to study the starting and operating characteristics of the system. Besides, two sets of experimental cases were carried out to explore the operating characteristics of the system under the frosting process. Results show that the maximum superheat degree is 11°C when the system starts in hot water mode, while the maximum superheat degree is more than 22°C when the system starts in the other modes. As the temperature of hot water rises when the system runs in hot water mode, the maximum value of the discharge pressure can reach 3.7MPa. Besides, the analysis parameters will have regular pulsations when the system is in cooling mode. For example, in the experimental case 5, the fluctuation range of the superheat degree is 5.1°C-16.2°C. [ABSTRACT FROM AUTHOR]

With the development of quantum computing and other fields, dilution refrigerators are required to have greater cooling capacity. More cooling power means larger 3He flow rate and the corresponding gas circulation system. In dry dilution refrigerators, 3He needs to be pressurized by compressor for the high inlet pressure. This paper introduces a dry dilution refrigerator driven by a designed high-power two-stage linear compressor, and the reliability of the compressor is verified by experiments. 3He can be pressurized to a pressure above 200 kPa at a flow rate of nearly 1 mmol/s and be condensed successfully in the condensatiion process. The refrigerator, precooled by a pulse tube cryocooler, can obtain a minimum temperature of 19 mK and a cooling capacity of 250 μW at about 100 mK at the total flow rate of about 0.45 mmol/s. The maximum power of 3He compressor can reach 300 W and the maximum compression ratio is over 10, which can be used as the 3He driver of high-power dilution refrigerators or closed-cycle space dilution refrigerators. [ABSTRACT FROM AUTHOR]