A dynamic receiver is included in parallel to an expander of a heating, ventilation, air conditioning, and refrigeration (HVACR) system. The dynamic receiver allows control of the refrigerant charge of the HVACR system to respond to different operating conditions. The dynamic receiver can be filled or emptied in response to the subcooling observed in the HVACR system compared to desired subcooling for various operating modes. The HVACR system can include a line directly conveying working fluid from compressor discharge to the dynamic receiver to allow emptying of the dynamic receiver to be assisted by injection of the compressor discharge.

A cooling system is designed to generally allow for one or more compressors to be bypassed when ambient temperatures are low. The system includes a bypass line and valve that opens when ambient temperatures are low and/or when the pressure of the refrigerant in the system is low. In this manner, the refrigerant can flow through the bypass line instead of through one or more compressors. These compressors may then be shut off. To supply any needed pressure to cycle the refrigerant, the system may include a pump that turns on when the bypass line is open. When ambient temperatures are extremely low, thermosiphon may be used to cycle the refrigerant.

A cooling system uses P-traps to address the oil return issues that result from a vertical separation between the compressor and the high side heat exchanger. Generally, the vertical piping that carries the refrigerant from the compressor to the high side heat exchanger includes P-traps installed at various heights to capture oil in the refrigerant and to prevent that oil from flowing back to the compressor. As oil collects in the P-traps, the refrigerant begins to push the oil upwards until the oil reaches the high side heat exchanger. Multiple piping of different sizes may be used depending on a discharge pressure of the compressor. When the discharge pressure is higher, a larger piping may be used direct the oil and refrigerant to the high side heat exchanger.

A refrigerant flow path switching unit, disposed between a heat source unit and a utilization unit and that switches a refrigerant flow in the utilization unit, includes: a flow path switching valve; a case that houses the flow path switching valve; and an electric component box that houses an electric component that controls the flow path switching valve. At least two surfaces of the case include a box attachment part that is configured to attach the electric component box to the case.

Leakage of a heating medium from a condenser or an evaporator can be quickly detected by a simple structure. A refrigeration apparatus 1 according to the present invention is formed by connecting a compressor 11, a condenser 12, an expansion valve 13 and an evaporator 14 by a pipe 15 such that a heating medium circulates therethrough in this order. The refrigeration apparatus 1 further includes a pressure detection unit 31, 32 that detects a pressure of the heating medium flowing through the pipe 15, and a control unit 41 that determines that leakage of the heating medium from the condenser 12 or the evaporator 14 has occurred, when a pressure detected by the pressure detection unit 31, 32 becomes not more than a predetermined value.

A heat source unit for an air conditioner that includes a refrigerant circuit, the heat source unit includes: an external housing; and a cooling heat exchanger disposed in the external housing and that is connected to the refrigerant circuit. The external housing accommodates: a compressor connected to the refrigerant circuit; a heat source heat exchanger that is connected to the refrigerant circuit and that exchanges heat between a refrigerant circulating in the refrigerant circuit and a heat source; and an electric box. The electrical box: includes a top and a plurality of side walls; accommodates electrical components that control the air conditioner; and further includes an air passage that includes an air inlet and an air outlet. An air flow is induced through the air passage from the air inlet to the air outlet for cooling at least some of the electrical components.

A refrigerant control system includes: a charge module configured to determine an amount of refrigerant that is present within a first portion of a refrigeration system within a building; and an isolation module configured to selectively open and close an isolation valve of the refrigeration system and to, via the isolation valve, maintain the amount of refrigerant within the first portion within the building below a predetermined amount of the refrigerant.

A first valve is connected between a compressor and a first heat exchanger. A second valve is connected between the first heat exchanger and a expansion valve. When a start condition of the heating operation is satisfied and when a specific condition is satisfied, a controller starts supplying refrigerant from the compressor to the first valve, and then, opens the first and second valves. The specific condition is a condition indicating that a first heat exchange capability of the first heat exchanger is higher than a second heat exchange capability of a second heat exchanger. When the start condition of the heating operation is satisfied and when the specific condition is not satisfied, the controller opens the first and second valves, and then starts supplying the refrigerant from the compressor to the first valve.

In a power converter, an inductance L of a reactor and a capacitance C of a capacitor satisfy a condition of the expression (1) below. In the power converter, a current-limiting circuit between an AC power source and the capacitor is unnecessary. Herein, αm ([A.Math.s]) is a value of a ratio of a maximum rated current squared time product to a maximum rated output current of diodes of a rectifier circuit, Pmax is a maximum power consumption of the motor, Vac is a voltage value of a three-phase AC voltage, and a value of a constant a is 4.3

[00001]$\begin{array}{cc}a.C.\sqrt{\frac{C}{L}}.Math.\frac{{\mathrm{Vac}}^3}{P_{\max }}\le {\alpha }_m.& \left(1\right)\end{array}$

A refrigeration cycle apparatus includes: a refrigeration cycle circuit in which a compressor, a condenser, a first expansion valve, and an evaporator are connected by refrigerant pipes; an injection pipe having a refrigerant inflow side end and a refrigerant outflow side end, the refrigerant inflow side being connected between the condenser and the first expansion valve, the refrigerant outflow side end being connected to a suction side of the compressor; a second expansion valve provided at the injection pipe; and a controller that controls a rotation speed of the compressor and an opening degree of the second expansion valve. In the case of reducing a heat-exchange capability of the evaporator when the rotation speed of the compressor is a specified rotation speed, the controller performs a low load operation during which refrigeration is caused to flow through the injection pipe.