REFRIGERATION CYCLE USING HEAT TRANSFER TUBE FOR ZEOTROPIC REFRIGERANT MIXTURE

摘要

PURPOSE: A refrigeration cycle using a heat transfer tube for a zeotropic refrigerant mixture is provided to obtain the improved heat transfer tube having high heat transfer performance and a freezer or an air conditioner having high coefficient of performance. CONSTITUTION: A refrigeration cycle comprises a compressor; a first heat exchanger(17) connected with the compressor; and a second heat exchanger(15) connected, at one end, with the first heat exchanger through an expansion valve, and at another end, with the compressor. At least one heat transfer tube of at least one of the first heat exchanger and the second heat exchanger has a plurality of helical ridges extending at a helical angle of 10 degrees to 20 degrees with respect to the axis of the tube, and secondary grooves crossing the ridges. The ridges have a pitch Pf1 such that when an inner diameter of the heat transfer tube is denoted by Di, a ratio Pf1/Di is within a range of 0.05 to 0.1. The secondary grooves have a depth Hf2 which is set within a range of 40 to 100% of a height Hf1 of the ridges, and a width Wf2 which is set between a top width Wt of the ridges and a bottom width Wb of the ridges. A cross-sectional shape of the secondary grooves provides the ridges with the secondary grooves with a heat transfer area, which is larger than a heat transfer area without the secondary grooves.