A refrigeration system is of the type that includes a refrigerant compressor unit which compresses normal refrigerating mass flow and a parallel compressor. The parallel compressor in a parallel compression mode of operation of the refrigerant circuit, sucks in refrigerant from the intermediate pressure accumulator and compresses it to high pressure. It is proposed that, in order to increase efficiency, the power of the parallel compressor is controlled by a control system. The control system determines at least one reference variable representing a load state of the refrigerant circuit, that determines a set intermediate pressure value on the basis of the at least one reference variable at least in a parallel compression mode of operation, and that regulates the intermediate pressure in accordance with the set intermediate pressure value at least in the parallel compression mode of operation.

A system and method of freeze protection for a chiller including a metering device in flow communication with a condenser, a controller in electrical communication with the metering device, wherein the controller is configured to determine whether the difference between the fluid characteristic of the first liquid and the fluid characteristic of the second liquid is greater than a freezing limit, and enter a freeze protection mode if the difference between the fluid characteristic of the first liquid and the fluid characteristic of the second liquid is greater than the freezing limit.

A dehumidification system includes a compressor, a primary evaporator, a primary condenser, a secondary evaporator, a secondary condenser, a modulating valve, and a liquid-cooled alternate condenser. The secondary evaporator receives an inlet airflow and outputs a first airflow to the primary evaporator. The primary evaporator receives the first airflow and outputs a second airflow to the secondary condenser. The secondary condenser receives the second airflow and outputs a third airflow to the primary condenser. The primary condenser receives the third airflow and outputs a dehumidified airflow. The compressor receives a flow of refrigerant from the primary evaporator and provides the flow of refrigerant to the modulating valve. The modulating valve directs the flow of refrigerant to the primary condenser and to the alternate condenser. The alternate condenser receives a portion of the flow of refrigerant and transfers heat from the refrigerant to a flow of fluid.

In a refrigeration system comprising a refrigerant circuit, a heat exchanger, an expansion element which, in the active state, cools the entire mass flow of the refrigerant by expansion and thereby produces a main mass flow consisting of liquid refrigerant and an auxiliary mass flow consisting of gaseous refrigerant which enter an intermediate pressure accumulator, at least one normal refrigerating stage which expands a normal refrigerating mass flow in at least one normal refrigerating expansion unit to a low pressure and thereby makes refrigerating capacity available for normal refrigerating purposes, a refrigerant compressor unit which compresses the normal refrigerating mass flow from low pressure to high pressure, and a parallel compressor which, in a parallel compression mode of operation of the refrigerant circuit, sucks in refrigerant from the intermediate pressure accumulator and compresses it to high pressure, it is proposed that, in order to increase the efficiency, the power of the parallel compressor be controlled by a control system, that the control system determine at least one reference variable representing a load state of the refrigerant circuit, that the control system determine a set intermediate pressure value on the basis of the at least one reference variable at least in a parallel compression mode of operation, and that the control system regulate the intermediate pressure in accordance with the set intermediate pressure value at least in the parallel compression mode of operation.

A system for maximizing the measured efficiency of an HVAC&R system including two pressure sensors, two temperature sensors, a flow sensor, a power voltage sensor, a power current sensor, and a controller. Each pressure sensor may be adapted to measure different refrigerant pressures and generate respective pressure signals. Each temperature sensor may be adapted to measure different refrigerant temperatures and generate respective temperature signals. The flow sensor may be adapted to measure a refrigerant flow rate and to generate a flow signal. The power voltage sensor may be configured to measure an electrical voltage input and generate a power voltage signal. The power current sensor configured to measure an electrical current input and to generate a power current signal. The controller may be adapted to receive the signals, calculate a measured efficiency, and output a first voltage output signal having a value dependent upon the measured efficiency.

A system for maximizing the measured efficiency of an HVAC&R system may include the steps of (1) providing a plurality of operating parameters selected from the group consisting of condenser fan speed, evaporator fan speed, inlet solenoid valve position, outlet solenoid valve position, and compressor control to the air conditioner or the heat pump system wherein each of the plurality of operating parameters has a respective operating parameter value; (2) calculating an initial efficiency of the system using signals received from a plurality of components selected from the group consisting of a temperature sensor, a humidity sensor, a pressure sensor, a flow sensor, a voltage sensor, and a current sensor; and (3) proceeding, starting with a first of the plurality of operating parameters, to iteratively adjust values of each of the plurality of operating parameters and accept the new values only if the measured efficiency increases.

A method of controlling a condenser fan of a heating, ventilating, and air-conditioning (HVAC) system based on a comparison of a refrigerant flow rate to maintain a valve position of an expansion valve. In the method, a controller modulates the condenser fan to maintain the valve position of the expansion valve at a valve position setpoint when the refrigerant flow rate is higher than the critical flow rate. The method also comprises controlling the speed of the condenser fan of the HVAC system to maintain a condensing measurement at a plurality of condensing measurement setpoints when the refrigerant flow rate is higher than the critical flow rate. The method also comprises controlling the speed of the condenser fan to maintain a condensing measurement at a plurality of condensing measurement setpoints when the condensing temperature measurement is higher than an ambient air temperature value plus at or around 5 F.

A dehumidification system includes a compressor, a primary evaporator, a primary condenser, a secondary evaporator, a secondary condenser, a modulating valve, and a liquid-cooled alternate condenser. The secondary evaporator receives an inlet airflow and outputs a first airflow to the primary evaporator. The primary evaporator receives the first airflow and outputs a second airflow to the secondary condenser. The secondary condenser receives the second airflow and outputs a third airflow to the primary condenser. The primary condenser receives the third airflow and outputs a dehumidified airflow. The compressor receives a flow of refrigerant from the primary evaporator and provides the flow of refrigerant to the modulating valve. The modulating valve directs the flow of refrigerant to the primary condenser and to the alternate condenser. The alternate condenser receives a portion of the flow of refrigerant and transfers heat from the refrigerant to a flow of fluid.

A system for maximizing the measured efficiency of an HVAC&R system including two pressure sensors, two temperature sensors, a flow sensor, a power voltage sensor, a power current sensor, and a controller. Each pressure sensor may be adapted to measure different refrigerant pressures and generate respective pressure signals. Each temperature sensor may be adapted to measure different refrigerant temperatures and generate respective temperature signals. The flow sensor may be adapted to measure a refrigerant flow rate and to generate a flow signal. The power voltage sensor may be configured to measure an electrical voltage input and generate a power voltage signal. The power current sensor configured to measure an electrical current input and to generate a power current signal. The controller may be adapted to receive the signals, calculate a measured efficiency, and output a first voltage output signal having a value dependent upon the measured efficiency.

Measured EER and COP are affected by the load under which an air conditioning, refrigeration or heating system is running; the load is a function of the evaporating and condensing temperatures. The invention makes adjustments for the purpose of maximizing measured EER and COP in a feedback loop utilized to optimize cooling or heating capacity relative to power consumed. The maximum EER is continuously achieved by incrementally adjusting each operating parameter to realize an incremental increase in EER, even as conditions such as ambient temperature are changing.