The present invention provides a system and method for an improved multistage, cascade refrigeration system using hot gas defrost to rid the evaporator of ice build-up which accumulates over time, while the air in the evaporator enclosure remains below the freezing point of water. The present invention thus provides greater defrost flexibility with increased ease of design and implementation than current refrigeration systems, which allows for more robust hot gas defrost function for multistage refrigeration systems, such that it is unaffected by temperature changes of the condensing fluid (ambient air temperature for air cooled condensers, water temperature for water cooled condensers), and can be readily adapted to any refrigerant suitable for a selected temperature range.

A divided aircraft galley refrigeration system is disclosed. In embodiments, the system includes an evaporating unit positioned within an aircraft galley. In another embodiment, the system includes a refrigeration and heat discharge unit positioned outside of the aircraft galley. In another embodiment, the system includes a liquid refrigerant pipe configured to fluidically couple the evaporating unit and the refrigeration and heat discharge unit. In another embodiment, the system includes a vapor refrigerant pipe configured to fluidically couple the evaporating unit and the refrigeration and heat discharge unit.

The invention relates to an electric vehicle cabin heating system and a control method. The system comprises a first refrigerant circuit and a second refrigerant circuit that are connected in parallel, wherein the circuits each comprise a gas-liquid separator and a compressor that are connected in series; the first refrigerant circuit further comprises a first expansion unit; the second refrigerant circuit further comprises a second expansion unit and a condenser; and the first expansion unit is connected to the second expansion unit and the condenser in parallel. Thus, rapid cabin heating and stable heating capacity are achieved, the dependence on a heater is eliminated, and an air-conditioning system is simplified. The method comprises: a refrigerant in the second refrigerant circuit undergoing pressure regulation via the second expansion unit and then entering the condenser to release heat for heating a cabin; and a refrigerant in the first refrigerant circuit undergoing throttling and pressure reduction via the first expansion unit and converges with the refrigerant in the second refrigerant circuit in the gas-liquid separator, and the converging refrigerant enters the compressor for cycling. Thus, the decoupling between the regulation of heating capacity and the temperatures and flow rate of exterior ambient air and cabin air is achieved, and the problems of insufficient heating capacity and frequent defrosting of a heat pump system at a low temperature are solved.

Described is a regulation apparatus for a refrigeration plant having defined therein a refrigerant fluid path and a plurality of devices arranged along the refrigerant fluid path. The regulation apparatus includes a first sensor arranged in a first point (P1), and preferably a second sensor arranged in a second point (P3), both along the refrigerant fluid path. The control unit controls a first value measured by the first sensor and obtains a first regulation request of a device deriving from the first measured value as well as a second value measured by the second sensor, or calculated for the second point, and derives a second regulation request of the device deriving from the second measured value, compares the first and second regulation requests and establishes which regulation request is greater. A control unit commands an actuation device to actuate the most effective regulation request of the refrigeration plant devices.

Described is a regulation apparatus for a refrigeration plant having defined therein a refrigerant fluid path and a plurality of devices arranged along the refrigerant fluid path. The regulation apparatus includes a first sensor arranged in a first point (P1) and a second sensor arranged in a second point (P3), each along the fluid path of the refrigeration plant, a control unit and an actuation device. The control unit controls a first value measured by the first sensor and obtains a first regulation request deriving from the first measured value as well as a second value measured by the second sensor and derives a second regulation request deriving from the second measured value, compares the first and second regulation requests, and establishes which regulation request is greater. The control unit also commands the actuation device to actuate the most effective regulation request of the refrigeration plant devices.

A dedicated outside air-conditioning system (DOAS) that may automatically generate variable subcooling refrigerant delivered to the evaporator; and modulate hot discharge gas to reduce the relative humidity of the discharge air from the DOAS. The DOAS may include fluid control valves configured to regulate delivery of the refrigerant in order to seamlessly flex between maximum latent capacity (minimum discharge dewpoint) and maximum sensible capacity (minimum leaving air discharge dry bulb temperature) to match load and/or ventilation air requirements.

When a refrigerant leakage sensor detects a leakage of refrigerant from a refrigeration cycle apparatus having an indoor unit and an outdoor unit, a refrigerant recovery operation is started. In the refrigerant recovery operation, refrigerant is recovered in an accumulator and afterward a pump down operation is performed. In recovery of refrigerant in the accumulator, refrigerant in a liquid phase is accumulated in the accumulator as a result of circulation of refrigerant by operating a compressor in the state where a liquid shut-off valve and a gas shut-off valve are opened. After recovery of refrigerant in the accumulator is ended, the refrigerant in a liquid phase is accumulated in an outdoor heat exchanger by the pump down operation for operating the compressor in the state where the liquid shut-off valve is closed.

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

A water distribution apparatus and method including cold and hot water supplies, a fan coil (or chilled beam device), a control valve having cold and hot water inlets and outlets, cold and hot water outputs configured to supply cold and hot water to the fan coil, cold and hot water return inlets configured to receive from the fan coil the water supplied by the cold and/or water outputs and outputting the cold and/or hot water to the cold and hot water supply lines, respectively, via the cold and hot water outlets, respectively. Cold and hot water is supplied from the cold and/or hot water outputs to the fan coil and received into the cold and hot water return inlets, respectively, and the cold and hot water supplied by the cold and hot water outputs to the fan coil is output to the cold and hot water supply lines, respectively.

A method for operating and controlling a vapor-compression cycle includes providing a system comprising an evaporator with a fan, a compressor, a condenser with a fan, an integrated expander, and a flash tank device with a vapor/liquid two-phase inlet and two outlets wherein a first outlet is a vapor outlet and a second outlet is a liquid outlet, and a metering valve; bringing a vapor-compression cycle up to steady-state at a fixed operating condition; opening the metering valve until the desired compressor suction superheat is achieved; and maintaining the desired degree of superheat by selectively increasing and decreasing superheat by reducing and increasing metering valve flow rate respectively.