An apparatus for staged startup of air-cooled low charged packaged ammonia refrigeration system includes motorized valves on condenser coil inlets, a main compressor discharge motorized valve, a bypass pressure regulator valve in the main compressor piping, and check valves on the condenser outlets. The condenser inlet motorized valves provide precise control of gas feed to the condensers, so pressure can build without collapsing oil pressure. The condenser outlet contains check valves to prevent liquid backflow during coil isolation. The compressor discharge line contains a motorized valve for regulating discharge pressure at start-up. The motorized valve in the compressor discharge piping includes a bypass with a pressure regulator for precise regulation at minimum discharge pressure. Once discharge pressure rises above the setpoint, the condenser inlet solenoid coils open one at a time. The discharge pressure regulating motorized valve simultaneously regulates the discharge pressure until the condenser maintains discharge pressure.

A refrigeration cycle apparatus according to the present invention performs cooling by circulation of refrigerant. The refrigeration cycle apparatus includes an evaporator, a condenser, a pump, a compressor, and a controller. The evaporator is arranged in a first space. The condenser is arranged in a second space. The pump is configured to compress refrigerant from the condenser and output the refrigerant to the evaporator. The compressor is configured to compress refrigerant from the evaporator and output the refrigerant to the condenser. The controller is configured to control the pump and the compressor to cool the first space. The controller is configured to turn on the pump after turn-on of the compressor while a temperature of the first space is higher than a temperature of the second space.

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 bypass line is described that is capable of equalizing pressure within an HVAC system. The bypass line can also cause less noise than other solutions. A bypass line under the present disclosure can comprise a line from a high pressure side to a low pressure side of an HVAC system. Valves and orifices can be disposed within the bypass line. The valves and orifices help to slow the speed of fluid from high pressure to low pressure locations, thus reducing noise during pressure equalization.

The present application provides a low load operating system for a refrigeration system having a compressor, a condenser, an expansion valve, and an evaporator. The low load operating system may include a hot gas bypass line extending from a discharge side of the compressor to a suction side of the compressor and a desuperheat line extending from upstream of the expansion valve to the suction side of the compressor.

A vapor compression refrigeration system has a main refrigerant circuit having a primary compressor group, a gas cooler or condenser, an expansion device, a liquid receiver, and at least one evaporator. An emergency circulation duct fluidically connects the liquid receiver to the main circuit to allow a flow of refrigerant from the liquid receiver to the gas cooler. An emergency compressor group in the emergency circulation duct is activatable when pressure inside the liquid receiver or in the duct upstream of the emergency compressor group meets or exceeds a predefined emergency pressure threshold. An uninterruptible power supply powers the emergency compressor group and expansion device during a shutdown of the refrigeration system. When pressure inside the liquid receiver or in the duct upstream of the emergency compressor group equals or exceeds the predefined emergency pressure threshold, an emergency circulation of refrigerant fluid is activated through the emergency circulation duct.

An apparatus includes a high side heat exchanger, a heat exchanger, a flash tank, a first expansion valve, a second expansion valve, a load, a first compressor, and a second compressor. During a first mode of operation, the second expansion valve directs refrigerant from the flash tank to the load. The refrigerant from the load bypasses the first compressor. The heat exchanger transfers heat from the refrigerant from the high side heat exchanger to the refrigerant from the load. The second compressor compresses the refrigerant from the heat exchanger. During a second mode of operation, the first expansion valve directs refrigerant from the flash tank to the load. The first compressor compresses the refrigerant from the load and the second compressor compresses the refrigerant from the first compressor before the refrigerant from the first compressor reaches the high side heat exchanger.

A cooling system includes an evaporator, connected through fluid lines to a first condenser, a second condenser, a compressor, and a thermal expansion valve. One or more valves are arranged in the fluid lines. The one or more valves operated to, in a first mode, circulate fluid between the evaporator the first condenser; in a second mode, circulate the fluid between a) the evaporator and the first condenser, and b) the evaporator, the second condenser, and the thermal expansion valve, and; in a third mode, circulate the fluid between a) the evaporator and the first condenser, and c) the evaporator, the compressor, the second condenser, and the thermal expansion valve.

A method of controlling a refrigeration system including a medium temperature refrigeration load and a low temperature refrigeration load. The method includes selectively bypassing refrigerant between a medium temperature suction group and a low temperature suction group via a bypass line using an electronic valve positioned in the bypass line. The method also includes controlling flow of refrigerant between the medium temperature suction group and the low temperature suction group via a controller communicatively coupled to the valve, and modulating the valve at any position between a closed position and a full open position to vary an amount of refrigerant flow between the medium temperature suction group and the low temperature suction group in response to determining, via the controller, one or both of a state of the medium temperature suction group and a state of the low temperature suction group.

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.