Abstract: A heating and cooling system includes an evaporator, a compressor, and a condenser. A heat exchanger, which may be an outdoor heat exchanger, is configured to receive the refrigerant from the condenser, to selectively extract heat from or to add heat to the refrigerant, and to transfer the refrigerant to the evaporator. First control valving, disposed between the condenser and the heat exchanger, is configured to regulate flow of the refrigerant from the condenser to the heat exchanger in a first mode of operation. Second control valving, disposed between the condenser and the heat exchanger, is configured to regulate flow of the refrigerant from the heat exchanger to the evaporator in a second mode of operation. The system may be operated in a variety of modes by appropriate control of the valving and other system components.

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: Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and multi-slab heat exchangers are provided that include fluid connections for transmitting fluid between groups of tubes. The fluid connections may include generally tubular members fluidly connected to manifold sections. The fluid connections also may include partitioned manifolds containing tubes of different heights. Multichannel tubes are also provided that include a bent section configured to locate a flow path near a leading edge of a tube within one section and near a trailing edge of the tube within another section.

Abstract: A heating and cooling system includes an evaporator, a compressor, and a condenser. A heat exchanger, which may be an outdoor heat exchanger, is configured to receive the refrigerant from the condenser, to selectively extract heat from or to add heat to the refrigerant, and to transfer the refrigerant to the evaporator. First control valving, disposed between the condenser and the heat exchanger, is configured to regulate flow of the refrigerant from the condenser to the heat exchanger in a first mode of operation. Second control valving, disposed between the condenser and the heat exchanger, is configured to regulate flow of the refrigerant from the heat exchanger to the evaporator in a second mode of operation. The system may be operated in a variety of modes by appropriate control of the valving and other system components.

Abstract: A system and method for controlling the volume ratio of a compressor is provided. The system can use a port (88) or ports in a rotor cylinder to bypass vapor from the compression chamber to the discharge passage of the compressor. A control valve (90) can be used to open or close the port or ports to obtain different volume ratios in the compressor. The control valve (90) can be moved or adjusted by one or more valves that control a flow of fluid to the valve. A control algorithm can be used to control the one or more valves to move the control valve to obtain different volume ratios from the compressor. The control algorithm can control the one or more valves in response to operating parameters associated with the compressor.

Abstract: Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and heat exchangers are provided that include multichannel tube configurations designed to reduce refrigerant pressure drop through a heat exchanger manifold. In certain embodiments, tubes inserted within the manifold adjacent to a refrigerant inlet have non-rectangular or recessed end profiles configured to increase flow area near the inlet, thereby reducing a pressure drop through the manifold. In further embodiments, insertion depths of the tubes within the manifold vary based on distance from the inlet. This configuration may establish a larger flow area adjacent to the inlet, thus reducing the pressure drop and increasing heat exchanger efficiency.

Abstract: Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and heat exchangers are provided that include multichannel tube configurations designed to promote flow of refrigerant within the multichannel tubes near the edges of the tubes that are contacted first by an external fluid. The tube configurations include flow paths of varying cross-sections, spacings, and sizes. Flow control mechanisms, such as inserts, blocking plates, sleeves, crimped sections, and crushed sections, may be employed with the flow paths to favor flow near the edges of the tubes that are contacted first by an external fluid.

Abstract: Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and heat exchangers are provided that include multichannel tube configurations designed to promote flow of refrigerant within the multichannel tubes near the edges of the tubes that are contacted first by an external fluid. The tube configurations include flow paths of varying cross-sections, spacings, and sizes. Flow control mechanisms, such as inserts, blocking plates, sleeves, crimped sections, and crushed sections, may be employed with the flow paths to favor flow near the edges of the tubes that are contacted first by an external fluid.

Abstract: A refrigeration system includes a chiller with an integrated free cooling system and refrigeration system. In certain embodiments, the chiller may be a single package unit with all equipment housed within the same support frame. The chiller may generally include three modes of operation: a first mode that employs free cooling, a second mode that employs free cooling and implements a refrigeration cycle, and a third mode that uses the free cooling system provide additional cooling capacity for the refrigeration system. The free cooling system includes an independent loop configured to transfer heat from a cooling fluid circulating within the free cooling system to the ambient air.

Abstract: Screw chillers have economizer systems that include a low pressure economizer and a high pressure economizer. According to certain embodiments, the low pressure economizer includes a flash tank, an expansion device and a flow control valve while the high pressure economizer includes a heat exchanger and an expansion device. The screw chillers also include a screw compressor that compresses refrigerant. The screw compressor includes a low pressure economizer port designed to receive lower pressure refrigerant from the flash tank within the low pressure economizer and a high pressure economizer port designed to receive higher pressure refrigerant from the heat exchanger within the higher pressure economizer. The screw compressor is designed to compress the refrigerant received from the evaporator, the refrigerant received through the low pressure economizer port, and the refrigerant received through the high pressure economizer port and to discharge the refrigerant through a common discharge.

Abstract: A heating, ventilation, air conditioning and refrigeration (HVAC&R) system having a compressor, a heat exchanger, an expansion valve, and a multichannel heat exchanger connected in a closed refrigerant loop. The multichannel heat exchanger has at least two fluid flow paths cooled by a flow of air from an air-moving device through the multichannel heat exchanger. Each of the at least two fluid flow paths have an inlet and an outlet in communication there between. The multichannel heat exchanger also has at least one flow regulator disposed in at least one outlet to regulate through at least one fluid flow path in response to the air flow through the heat exchanger to achieve a substantially equal temperature of a fluid flowing in the at least two flow paths.

Abstract: A system is provided for adjusting the volume ratio of a screw compressor. The system can use a port in a rotor cylinder to bypass vapor from the compression chamber to the discharge passage of the compressor. A valve can be used to open or close the port to obtain different volume ratios in the compressor.

Abstract: Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and multi-slab heat exchangers are provided that include fluid connections for transmitting fluid between groups of tubes. The fluid connections may include generally tubular members fluidly connected to manifold sections. The fluid connections also may include partitioned manifolds containing tubes of different heights. Multichannel tubes are also provided that include a bent section configured to locate a flow path near a leading edge of a tube within one section and near a trailing edge of the tube within another section.

Abstract: A heat exchanger is provided with stacked coil sections. Each of the stacked coil sections is configured to circulate a fluid independent from the other coil section. An air moving device is used to circulate air through both of the stacked coil sections. The stacked coil sections are positioned to have the air exiting the one coil section entering the other coil section.

Abstract: Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and heat exchangers are provided which include dissimilar tube spacing configurations. The heat exchangers include multiple sets of multichannel tubes in fluid communication with each other. One set of multichannel tubes contains a plurality of tubes spaced apart at one spacing while the another set of multichannel tubes contains a plurality of tubes spaced apart at a different spacing. The different spacing between the multichannel tubes allows each set of tubes to be configured to the properties of the refrigerant flowing within the tubes.

Abstract: A vapor compression system that circulates a fluid through a closed loop interconnecting a compressor, a first heat exchanger, a flow-restricting expansion device, and a second heat exchanger. The system further includes a vessel in a first fluid communication and a selective second fluid communication with the loop between the compressor and the first heat exchanger with each of the first and second fluid communication configured to receive fluid from the loop. The vessel is in a third fluid communication with the first heat exchanger configured to provide fluid to the first heat exchanger. In response to a predetermined ambient temperature surrounding the system, the second fluid communication is selectively opened to provide an increased fluid flow from the vessel to the first heat exchanger.

Abstract: Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and multi-slab heat exchangers are provided that include fluid connections for transmitting fluid between groups of tubes. The fluid connections may include generally tubular members fluidly connected to manifold sections. The fluid connections also may include partitioned manifolds containing tubes of different heights. Multichannel tubes are also provided that include a bent section configured to locate a flow path near a leading edge of a tube within one section and near a trailing edge of the tube within another section.

Abstract: Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and heat exchangers are provided that include multichannel tube configurations designed to reduce refrigerant pressure drop through a heat exchanger manifold. In certain embodiments, tubes inserted within the manifold adjacent to a refrigerant inlet have non-rectangular or recessed end profiles configured to increase flow area near the inlet, thereby reducing a pressure drop through the manifold. In further embodiments, insertion depths of the tubes within the manifold vary based on distance from the inlet. This configuration may establish a larger flow area adjacent to the inlet, thus reducing the pressure drop and increasing heat exchanger efficiency.

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: An HVAC system having a main circuit and a subcooler circuit. The main circuit includes a main circuit evaporator, a main circuit expansion device, a main circuit condenser and a main circuit compressor connected in a closed refrigerant loop. The subcooler circuit includes a subcooler evaporator, a subcooler expansion device, a subcooler condenser and a subcooler compressor connected in a closed refrigerant loop. The subcooler evaporator is arranged and disposed to exchange heat between liquid refrigerant in the main circuit and the refrigerant in the subcooler circuit to cool the liquid refrigerant in the main circuit prior to entering the main circuit evaporator. The operation of the subcooler circuit provides an increased cooling capacity per unit of a mass flow of cooling fluid through the main circuit condenser and subcooler condenser for the HVAC system with a predetermined design efficiency.