Abstract: A refrigeration unit comprising a cooling circuit having a compressor, a condenser and an evaporator, and said unit including a hot gas valve and a hot gas bypass passage bypassing the condenser and forming a defrost circuit, so that when the evaporator is frosted upon operation by means of the cooling circuit, constant quantity refrigerant is circulated around the defrost circuit to perform a defrosting operation.

Abstract: A refrigeration unit comprising a cooling circuit having a compressor, a condenser and an evaporator, and said unit including a hot gas valve and a hot gas bypass passage bypassing the condenser and forming a defrost circuit, so that when the evaporator is frosted upon operation by means of the cooling circuit, constant quantity refrigerant is circulated around the defrost circuit to perform a defrosting operation.

Abstract: A refrigeration equipment having a compressor, a condenser, an evaporator and a thermostatic expansion valve with an equalizer line and capable of controlling its refrigeration capacity, wherein incorporated are a hot gas by-pass passage and a hot gas valve installed thereon to introduce the hot gas into said evaporator by by-passing said condensor and thermostatic expansion valve, a control passage to introduce, during the hot gas by-pass operation, a portion of hot gas to said equalizer line and throttle the opening of said expansion valve and a communication shut-off valve to shut off, at the close of said hot gas valve, the communication between said control passage and equalizer line, whereby controlling the opening of said expansion valve in accordance with hot gas by-passed during the capacity control by use of hot gas, so that the control range of said refrigeration capacity can be extended.