Abstract: A heat pump apparatus has a main refrigerant circuit constituted by a closed loop including a compressor, condenser, gas-liquid separator, pressure reducer such as an expansion valve, and an evaporator. A shunting refrigerant line having a compressor, condenser and a pressure reducer means shunts from the gaseous phase portion of the gas-liquid separator of the main refrigerant circuit and merges in the evaporator of the main refrigerant circuit. The shunting refrigerant line may be constructed to have one or more compression stages.

Abstract: An expansion valve has a refrigerant inlet passage, a refrigerant outlet passage, a valve chest to which both the passages open, a diaphragm chamber communicating with a heat-sensitive bulb through a tube of small diameter, and a valve body actuated in response to the operation of a diaphragm, the valve body being disposed facing a valve seat in the valve chest to regulate a passage defined between the valve seat and the valve body, to thereby control the flow rate of a refrigerant. The valve seat is adapted to be axially movable along the inner wall of the valve chest. In addition, means are provided for moving the valve seat in accordance with a change in pressure in the refrigerant circuit.

Abstract: A refrigerating apparatus comprises two refrigerant circuits connected in a parallel fashion which include a common condenser. An evaporating temperature in an evaporator of one refrigerant circuit is set to a relatively high temperature compared with that of an evaporator of the other refrigerant circuit, so that a two-temperature evaporation type refrigerating apparatus is formed and a compressor of one refrigerant circuit can be intermittently driven for each predetermined time period in a forced manner. In a defrosting mode, the condenser is made to operate as an evaporator, whereby the evaporator included in the other refrigerant circuit is defrosted.

Abstract: A refrigerating apparatus including a first compressor, a condenser, a first pressure reducer a first evaporator, a second pressure reducer and a second evaporator connected together by lines to form a refrigerating circuit for a refrigerant to flow therethrough, wherein a second compressor is connected at its suction side to the second pressure reducer for receiving gaseous component of refrigerant from the first evaporator and connected at its discharge side to the line between the first compressor and the condenser. An evaporative pressure control valve may be mounted in the line between the first evaporator and the second pressure reducer or the line between the second pressure reducer and the second evaporator. A bypass line mounting an electromagnetic valve may connect the line between the first evaporator and the second pressure reducer to the line between the second pressure reducer and the second evaporator.

Abstract: A refrigerating system having, arranged to form a closed circuit, a refrigerant compressor, a condensor, a receiver and a plurality of sets of evaporators and expansion valves with all the sets connected in parallel with one another. The system further includes a throttle mounted in the circuit between the condenser and the receiver, a branch line and change-over valves for selectively connecting the circuit on the delivery side of the compressor to each evaporator and a passage connecting each evaporator to the receiver by bypassing the associated expansion valve, so that the refrigerantin the state of a compressed gas can be supplied to a desired evaporator to defrost the same and the refrigerant condensed in the defrosted evaporator can be returned to the receiver.