An efficient pulse tube cryocooler for boil-off gas reliquefaction in liquid natural gas tanks

Small liquid natural gas (LNG) distribution stations require compact, highly efficient cryocoolers to reliquefy boil-off gas in the LNG tank. This paper describes a pulse tube cryocooler measuring 420 mm x 690 mm x 780 mm and weighing 180 kg. With low input electric power, the relative Carnot efficiency exceeded 20%. Increasing the power to 10 kW, the cryocooler produced approximately 1.2 kW of cooling at 120 K. Approximately 295 normal cubic meters of boil-off natural gas per day can be condensed. If heat transfer in the main heat exchanger is improved, cooling power and efficiency could be further improved. This development offers an efficient, compact, and reliable configuration for energy saving in LNG distribution stations. (C) 2015 Elsevier Ltd. All rights reserved.