Abstract: A refrigeration system includes a heat exchanger configured to place a cooling fluid in a heat exchange relationship with a working fluid, a free-cooling circuit having a pump configured to circulate the working fluid through the heat exchanger and a condenser, a flow control valve configured to control a flow rate of the working fluid to the condenser, a condenser bypass valve configured to control a flow rate of the working fluid that bypasses the condenser, and a controller configured to adjust a position of the flow control valve, a position of the condenser bypass valve, a speed of a fan of the condenser, a speed of the pump, and a temperature of a heater based on an ambient temperature, a temperature of the working fluid leaving the condenser, the position of the flow control valve, the position of the condenser bypass valve, or a combination thereof.

Abstract: A refrigeration system includes a heat exchanger configured to place a cooling fluid in a heat exchange relationship with a working fluid, a free-cooling circuit having a pump configured to circulate the working fluid through the heat exchanger and a condenser, a flow control valve configured to control a flow rate of the working fluid to the condenser, a condenser bypass valve configured to control a flow rate of the working fluid that bypasses the condenser, and a controller configured to adjust a position of the flow control valve, a position of the condenser bypass valve, a speed of a fan of the condenser, a speed of the pump, and a temperature of a heater based on an ambient temperature, a temperature of the working fluid leaving the condenser, the position of the flow control valve, the position of the condenser bypass valve, or a combination thereof.

Abstract: A refrigeration system includes a heat exchanger configured to place a cooling fluid in a heat exchange relationship with a working fluid, a free-cooling circuit having a pump configured to circulate the working fluid through the heat exchanger and a condenser, a flow control valve configured to control a flow rate of the working fluid to the condenser, a condenser bypass valve configured to control a flow rate of the working fluid that bypasses the condenser, and a controller configured to adjust a position of the flow control valve, a position of the condenser bypass valve, a speed of a fan of the condenser, a speed of the pump, and a temperature of a heater based on an ambient temperature, a temperature of the working fluid leaving the condenser, the position of the flow control valve, the position of the condenser bypass valve, or a combination thereof.

Abstract: Embodiments of the present disclosure relate to a heating, ventilating, air conditioning, and refrigeration (HVAC&R) system that includes a variable speed drive (VSD) configured to supply power to a motor configured to drive a compressor of the HVAC&R system, a rectifier of the VSD configured to receive alternating current (AC) power from an AC power source and convert the AC power to direct current (DC) power, a DC bus of the VSD electrically coupled to the rectifier, an inverter of the VSD electrically coupled to the DC bus, where the inverter is configured to convert the DC power to output AC power, the output AC power has a variable voltage and a variable frequency, and the output AC power is directed to the motor, and a battery electrically coupled to the DC bus, where the battery is configured to provide auxiliary DC power to the VSD.

Abstract: Embodiments of the present disclosure relate to a heating, ventilating, air conditioning, and refrigeration (HVAC&R) system that includes a variable speed drive (VSD) configured to supply power to a motor configured to drive a compressor of the HVAC&R system, a rectifier of the VSD configured to receive alternating current (AC) power from an AC power source and convert the AC power to direct current (DC) power, a DC bus of the VSD electrically coupled to the rectifier, an inverter of the VSD electrically coupled to the DC bus, where the inverter is configured to convert the DC power to output AC power, the output AC power has a variable voltage and a variable frequency, and the output AC power is directed to the motor, and a battery electrically coupled to the DC bus, where the battery is configured to provide auxiliary DC power to the VSD.

Abstract: A refrigeration system includes a heat exchanger configured to place a cooling fluid in a heat exchange relationship with a working fluid, a free-cooling circuit having a pump configured to circulate the working fluid through the heat exchanger and a condenser, a flow control valve configured to control a flow rate of the working fluid to the condenser, a condenser bypass valve configured to control a flow rate of the working fluid that bypasses the condenser, and a controller configured to adjust a position of the flow control valve, a position of the condenser bypass valve, a speed of a fan of the condenser, a speed of the pump, and a temperature of a heater based on an ambient temperature, a temperature of the working fluid leaving the condenser, the position of the flow control valve, the position of the condenser bypass valve, or a combination thereof.

Abstract: A refrigeration system is provided, such as for use with chillers. The system uses a tube-side condenser, such as a microchannel condenser, along with a shell-side evaporator such as a falling film evaporator. A flash tank economizer is disposed between the condenser and the evaporator, and an inlet valve to the flash tank is controlled based upon subcooling of condensate from the condenser. The vapor exiting the flash tank may be fed via an economizer line to a system compressor. Liquid phase refrigerant combined with some gas phase refrigerant exits the flash tank and is directed through an orifice before entering the evaporator.

Abstract: A method for controlling an economizer circuit is provided. The economizer circuit includes a valve to regulate refrigerant flow between the economizer and the compressor. The valve can be opened to engage the economizer circuit or closed to disengage the economizer circuit based on the output frequency provided to the compressor motor by a variable speed drive and an operating condition of the economizer.

Abstract: A refrigeration system is provided, such as for use with chillers. The system uses a tube-side condenser, such as a microchannel condenser, along with a shell-side evaporator such as a falling film evaporator. A flash tank economizer is disposed between the condenser and the evaporator, and an inlet valve to the flash tank is controlled based upon subcooling of condensate from the condenser. The vapor exiting the flash tank may be fed via an economizer line to a system compressor. Liquid phase refrigerant combined with some gas phase refrigerant exits the flash tank and is directed through an orifice before entering the evaporator.

Abstract: A refrigeration system is provided, such as for use with chillers. The system uses a tube-side condenser, such as a microchannel condenser, along with a shell-side evaporator such as a falling film evaporator. A flash tank economizer is disposed between the condenser and the evaporator, and an inlet valve to the flash tank is controlled based upon subcooling of condensate from the condenser. The vapor exiting the flash tank may be fed via an economizer line to a system compressor. Liquid phase refrigerant combined with some gas phase refrigerant exits the flash tank and is directed through an orifice before entering the evaporator.

Abstract: A method for controlling an economizer circuit is provided. The economizer circuit includes a valve to regulate refrigerant flow between the economizer and the compressor. The valve can be opened to engage the economizer circuit or closed to disengage the economizer circuit based on the output frequency provided to the compressor motor by a variable speed drive and an operating condition of the economizer.

Abstract: A system and method for controlling an economizer circuit is provided. The economizer circuit includes a valve to regulate refrigerant flow between the economizer and the compressor. The valve can be opened to engage the economizer circuit or closed to disengage the economizer circuit based on the output frequency provided to the compressor motor by a variable speed drive and an operating condition of the economizer.

Abstract: Methods and systems for controlling the operation of condenser fans are provided. At most discharge pressures, the operation of the condenser fans may be controlled based on a capacity of the compressor system. To adjust operation of the condenser fans, the speed of the fans and/or the number or operational fans may be adjusted. The control of the condenser fans based on compressor system capacity may be overridden at compressor discharge pressures that rise above a high pressure level and fall below a low pressure level. At the high and low discharge pressures, the fan speed and/or number of operating fans may be adjusted based solely on the discharge pressure rather than on the compressor system capacity.

Abstract: A system and method for controlling an economizer circuit is provided. The economizer circuit includes a valve to regulate refrigerant flow between the economizer and the compressor. The valve can be opened to engage the economizer circuit or closed to disengage the economizer circuit based on the output frequency provided to the compressor motor by a variable speed drive and an operating condition of the economizer.

Abstract: Methods and systems for controlling the operation of condenser fans are provided. At most discharge pressures, the operation of the condenser fans may be controlled based on a capacity of the compressor system. To adjust operation of the condenser fans, the speed of the fans and/or the number or operational fans may be adjusted. The control of the condenser fans based on compressor system capacity may be overridden at compressor discharge pressures that rise above a high pressure level and fall below a low pressure level. At the high and low discharge pressures, the fan speed and/or number of operating fans may be adjusted based solely on the discharge pressure rather than on the compressor system capacity.

Abstract: A refrigeration system is provided, such as for use with chillers. The system uses a tube-side condenser, such as a microchannel condenser, along with a shell-side evaporator such as a falling film evaporator. A flash tank economizer is disposed between the condenser and the evaporator, and an inlet valve to the flash tank is controlled based upon subcooling of condensate from the condenser. The vapor exiting the flash tank may be fed via an economizer line to a system compressor. Liquid phase refrigerant combined with some gas phase refrigerant exits the flash tank and is directed through an orifice before entering the evaporator.

Abstract: A capacity control algorithm for a multiple compressor liquid chiller system is provided wherein the speed and number of compressors in operation are controlled in order to obtain a leaving liquid temperature setpoint. In response to an increase in the load in the chiller system, the algorithm determines if a compressor should be started and adjusts the operating speed of all operating compressors when an additional compressor is started. In response to a decrease in the load in the chiller system with multiple compressors operating, the algorithm determines if a compressor should be de-energized and adjusts the operating speed of all remaining operating compressors when a compressor is de-energized.

Abstract: A capacity control algorithm for a multiple compressor liquid chiller system is provided wherein the speed and number of compressors in operation are controlled in order to obtain a leaving liquid temperature setpoint. In response to an increase in the load in the chiller system, the algorithm determines if a compressor should be started and adjusts the operating speed of all operating compressors when an additional compressor is started. In response to a decrease in the load in the chiller system with multiple compressors operating, the algorithm determines if a compressor should be de-energized and adjusts the operating speed of all remaining operating compressors when a compressor is de-energized.

Abstract: A capacity control algorithm for a multiple compressor liquid chiller system is provided wherein the speed and number of compressors in operation are controlled in order to obtain a leaving liquid temperature setpoint. In response to an increase in the load in the chiller system, the algorithm determines if a compressor should be started and adjusts the operating speed of all operating compressors when an additional compressor is started. In response to a decrease in the load in the chiller system with multiple compressors operating, the algorithm determines if a compressor should be de-energized and adjusts the operating speed of all remaining operating compressors when a compressor is de-energized.

Abstract: A variable speed drive is provided having a converter to convert an AC voltage to a DC voltage, a DC link to filter and store energy from the converter, and a plurality of inverters, wherein each inverter is configured to convert a DC voltage to an AC voltage to power a corresponding load connected to the inverter The converter is electrically connected to an AC power source, the DC link is electrically connected to the converter, and the plurality of inverters are electrically connected in parallel to the DC link. Each inverter of the plurality of inverters is configured to operate substantially independently of other inverters of the plurality of inverters.