Abstract: A method of controlling an HVACR unit in an HVACR system including an HVACR unit through which a process fluid is pumped to meet a temperature control demand includes monitoring, by a controller, a flowrate of the process fluid through the HVACR unit. When the flowrate of the process fluid is above a minimum flowrate threshold, the process fluid is provided to one or more terminals in the HVACR system according to the temperature control demand. A bypass flow of the process fluid through a bypass line is disabled by changing a state of a valve fluidly connected to the bypass line and one of the one or more terminals to a flow disabled state. When the flowrate of the process fluid is below the minimum flowrate threshold, the controller enables the bypass flow of the process fluid through the bypass line.

Abstract: Control systems and methods for control of heating, ventilation, air conditioning, and refrigeration (HVACR) systems that include cooling and one or both of heating and heat recovery can include adaptive and balanced modes for each of heating and cooling operations. The adaptive heating and cooling modes each respectively include controlling the HVACR system to achieve a target temperature for the respective heating or cooling process fluid and to unload or stop the compressor when the temperature of a the other of the cooling or heating process fluid exceeds a threshold. The balanced heating and cooling modes respectively include controlling a quantity of flow of the cooling or heating process fluids to meet balanced heating or cooling target temperatures for the respective heating or cooling process fluids and also the other of the cooling or heating process fluid.

Abstract: Control systems and methods for control of heating, ventilation, air conditioning, and refrigeration (HVACR) systems that include cooling and one or both of heating and heat recovery can include adaptive and balanced modes for each of heating and cooling operations. The adaptive heating and cooling modes each respectively include controlling the HVACR system to achieve a target temperature for the respective heating or cooling process fluid and to unload or stop the compressor when the temperature of a the other of the cooling or heating process fluid exceeds a threshold. The balanced heating and cooling modes respectively include controlling a quantity of flow of the cooling or heating process fluids to meet balanced heating or cooling target temperatures for the respective heating or cooling process fluids and also the other of the cooling or heating process fluid.

Abstract: A method of controlling an HVACR unit in an HVACR system including an HVACR unit through which a process fluid is pumped to meet a temperature control demand includes monitoring, by a controller, a flowrate of the process fluid through the HVACR unit. When the flowrate of the process fluid is above a minimum flowrate threshold, the process fluid is provided to one or more terminals in the HVACR system according to the temperature control demand. A bypass flow of the process fluid through a bypass line is disabled by changing a state of a valve fluidly connected to the bypass line and one of the one or more terminals to a flow disabled state. When the flowrate of the process fluid is below the minimum flowrate threshold, the controller enables the bypass flow of the process fluid through the bypass line.

Abstract: A multi-mode, bi-directional cascade heat pump system, according to some examples, includes at least two chillers each being part of a unidirectional refrigerant circuit. The system includes heat exchangers each of which are dedicated to operate as just a condenser or as just an evaporator, regardless of the system's operating mode. In some modes, a secondary fluid transfers heat between the condenser of one chiller and the evaporator of another chiller before the fluid returns to a secondary fluid source such as, for example, a geothermal borefield or a conventional water source. In some embodiments, fluid is withdrawn from a borefield by way of a pump having a speed that varies to maintain a desired fluid temperature and/or a desired heat transfer rate at the borefield. The heat pump system includes means for minimizing flow through the borefield and for minimizing unnecessary mixing of relatively high and low temperature fluid.

Abstract: A multi-mode, bi-directional cascade heat pump system, according to some examples, includes at least two chillers each being part of a unidirectional refrigerant circuit. The system includes heat exchangers each of which are dedicated to operate as just a condenser or as just an evaporator, regardless of the system's operating mode. In some modes, a secondary fluid transfers heat between the condenser of one chiller and the evaporator of another chiller before the fluid returns to a secondary fluid source such as, for example, a geothermal borefield or a conventional water source. In some embodiments, fluid is withdrawn from a borefield by way of a pump having a speed that varies to maintain a desired fluid temperature and/or a desired heat transfer rate at the borefield. The heat pump system includes means for minimizing flow through the borefield and for minimizing unnecessary mixing of relatively high and low temperature fluid.

Abstract: A multi-mode, bi-directional cascade heat pump system, according to some examples, includes at least two chillers each being part of a unidirectional refrigerant circuit. The system includes heat exchangers each of which are dedicated to operate as just a condenser or as just an evaporator, regardless of the system's operating mode. In some modes, a secondary fluid transfers heat between the condenser of one chiller and the evaporator of another chiller before the fluid returns to a secondary fluid source such as, for example, a geothermal borefield or a conventional water source. In some embodiments, fluid is withdrawn from a borefield by way of a pump having a speed that varies to maintain a desired fluid temperature and/or a desired heat transfer rate at the borefield. The heat pump system includes means for minimizing flow through the borefield and for minimizing unnecessary mixing of relatively high and low temperature fluid.

Abstract: A multi-mode, bi-directional cascade heat pump system, according to some examples, includes at least two chillers each being part of a unidirectional refrigerant circuit. The system includes heat exchangers each of which are dedicated to operate as just a condenser or as just an evaporator, regardless of the system's operating mode. In some modes, a secondary fluid transfers heat between the condenser of one chiller and the evaporator of another chiller before the fluid returns to a secondary fluid source such as, for example, a geothermal borefield or a conventional water source. In some embodiments, fluid is withdrawn from a borefield by way of a pump having a speed that varies to maintain a desired fluid temperature and/or a desired heat transfer rate at the borefield. The heat pump system includes means for minimizing flow through the borefield and for minimizing unnecessary mixing of relatively high and low temperature fluid.

Abstract: A multi-mode, bi-directional cascade heat pump system, according to some examples, includes at least two chillers each being part of a unidirectional refrigerant circuit. The system includes heat exchangers each of which are dedicated to operate as just a condenser or as just an evaporator, regardless of the system's operating mode. In some modes, a secondary fluid transfers heat between the condenser of one chiller and the evaporator of another chiller before the fluid returns to a secondary fluid source such as, for example, a geothermal borefield or a conventional water source. In some embodiments, fluid is withdrawn from a borefield by way of a pump having a speed that varies to maintain a desired fluid temperature and/or a desired heat transfer rate at the borefield. The heat pump system includes means for minimizing flow through the borefield and for minimizing unnecessary mixing of relatively high and low temperature fluid.

Abstract: A multi-mode, bi-directional cascade heat pump system, according to some examples, includes at least two chillers each being part of a unidirectional refrigerant circuit. The system includes heat exchangers each of which are dedicated to operate as just a condenser or as just an evaporator, regardless of the system's operating mode. In some modes, a secondary fluid transfers heat between the condenser of one chiller and the evaporator of another chiller before the fluid returns to a secondary fluid source such as, for example, a geothermal borefield or a conventional water source. In some embodiments, fluid is withdrawn from a borefield by way of a pump having a speed that varies to maintain a desired fluid temperature and/or a desired heat transfer rate at the borefield. The heat pump system includes means for minimizing flow through the borefield and for minimizing unnecessary mixing of relatively high and low temperature fluid.

Abstract: To provide chilled water, a variable-primary-flow system includes two variable speed pumps that pump water through a first chiller and a second chiller. A control energizes the second chiller in response to a cooling demand exceeding that what can be met by the first chiller operating alone, and de-energizes the second chiller upon the cooling demand decreasing to a level below the first chiller's maximum capacity. When both chillers are operating, the capacities of the chillers are modulated in unison to meet the cooling demand. Likewise, when both pumps are running, their speed is modulated in unison to provide a desired pressure.

Abstract: To provide chilled water, a variable-primary-flow system includes two variable speed pumps that pump water through a first chiller and a second chiller. A control energizes the second chiller in response to a cooling demand exceeding that what can be met by the first chiller operating alone, and de-energizes the second chiller upon the cooling demand decreasing to a level below the first chiller's maximum capacity. When both chillers are operating, the capacities of the chillers are modulated in unison to meet the cooling demand. Likewise, when both pumps are running, their speed is modulated in unison to provide a desired pressure.

Abstract: A method of minimizing energy use in a chiller and cooling tower system is disclosed. The method comprises the steps of: determining a measure of chiller efficiency; determining a measure of cooling tower efficiency; determining a measure of the transfer rate of heat energy between the cooling tower and the chiller; calculating a near optimal water temperature as a function of the chiller work efficiency, the cooling tower efficiency and the transfer rate; and operating the cooling tower to provide a conditioned fluid at the temperatures to produce near optimal energy consumption.