Abstract.A pulse tube cryocooler with 50 W cooling capacity at 77 K is developed to cool superconducting devices mounted on automobiles. The envisioned cryocooler weight is less than 40 kg, and the input electric power is less than 1 kW. To achieve these requirements, the working frequency is increased to 75 Hz, and the dual-opposed pistons use gas bearings to reduce compressor weight and volume. The heat from the main heat exchanger is rejected by forced convective air instead of water. The compressor and the cold finger are carefully matched to improve the efficiency. The details of these will be presented in this paper. After some adjustment, a no load temperature for the pulse tube cryocooler of 40 K was achieved with 1 kW input electric power in surroundings at 298 K. At 77 K, the cooling capacity is 50 W. If the main heat exchanger is cooled by water at 293 K, the cooling capacity increases to 64 W, corresponding to a relative Carnot efficiency of 18%.
Small liquid natural gas (LNG) distribution stations require compact, highly efficient cryocoolers to condense boil-off gas in the LNG tank. This paper reports a pulse tube cryocooler measuring 420*690*780 mm and weighing 180 kg. Using low input electric power, the relative Carnot efficiency was greater than 20%. Increasing the power to 11 kW, the cryocooler produced approximately 1.2 kW of cooling at 120 K. Approximately 293 normal cubic meters of boiloff NG per day can be condensed. If heat transfer in the main heat exchanger was improved, cooling power and efficiency could be improved. It presents a new efficient, compact and reliable configuration for the energy saving in LNG distribution stations.
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