HEAT PUMP SYSTEM

PROBLEM TO BE SOLVED: To achieve highly efficient and stable operation of a heat pump system even when an inclination of a state change line in a compression stroke of a compressor becomes steeper than an inclination of a saturated vapor line between the suction pressure and the discharge pressure of the compressor.SOLUTION: The heat pump system includes: discharge pressure detection means 21 provided in a circulation line 16 between a compressor 11 and a condenser 12; discharge temperature detection means 22; suction pressure detection means 31 which detects the suction pressure of a working medium sucked into the compressor 11; and evaporator outlet-side evaporating medium temperature detection means 32 which detects a temperature of an evaporating medium flowing out of an evaporator 14. The heat pump system also controls an opening of a circulation line expansion valve 13 so that an overheat degree of the working medium in a compression stroke of the compressor 11 reaches a prescribed value or higher on the basis of detection values of the discharge pressure detection means 21, the discharge temperature detection means 22, the suction pressure detection means 31 and the evaporator outlet-side evaporating medium temperature detection means 32. 【課題】ヒートポンプシステムにおいて、圧縮機の圧縮行程における状態変化線の傾きが、圧縮機の吸込圧力と吐出圧力との間の飽和蒸気線の傾きより急峻となる場合であっても、高効率かつ安定した運転を実現する。【解決手段】圧縮機１１と凝縮器１２との間の循環ライン１６に設けられた吐出圧力検出手段２１、吐出温度検出手段２２、圧縮機１１に吸い込まれる作動媒体の吸込圧力を検出する吸込圧力検出手段３１、および蒸発器１４から流出された蒸発用媒体の温度を検出する蒸発器出口側蒸発用媒体温度検出手段３２を備え、吐出圧力検出手段２１、吐出温度検出手段２２、吸込圧力検出手段３１、および蒸発器出口側蒸発用媒体温度検出手段３２での検出値に基づいて、圧縮機１１の圧縮行程における作動媒体の過熱度が所定の値以上となるように、循環ライン膨張弁１３の開度を制御する。【選択図】図１