A dehumidification system includes a compressor, a primary evaporator, a primary condenser, a secondary evaporator, and a secondary 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 primary condenser.

A refrigerant-amount determination kit includes a sensor and a processor. The sensor is mounted at least temporarily on at least one of a portion of a refrigeration cycle apparatus and the periphery of the refrigeration cycle apparatus. The refrigeration cycle apparatus is an apparatus having a refrigerant circuit that includes a compressor, a condenser, and an evaporator. The processor determines the amount of a refrigerant in the refrigerant circuit based on a detection result detected by the sensor during operation of the refrigeration cycle apparatus.

A dehumidification system includes a compressor, a primary evaporator, a primary condenser, a secondary evaporator, a secondary condenser, a modulating valve, and an 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 for heat rejection, where the primary condenser receives the remaining portion of the flow of refrigerant.

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.

A dehumidification system includes a compressor, a primary evaporator, a primary condenser, a secondary evaporator, and a secondary 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 primary condenser.

A dehumidification system includes a compressor, a primary evaporator, a primary condenser, a secondary evaporator, a secondary condenser, a modulating valve, and an 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 for heat rejection, where the primary condenser receives the remaining portion of the flow of refrigerant.

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 refrigerant-amount determination kit includes a sensor and a processor. The sensor is mounted at least temporarily on at least one of a portion of a refrigeration cycle apparatus and the periphery of the refrigeration cycle apparatus. The refrigeration cycle apparatus is an apparatus having a refrigerant circuit that includes a compressor, a condenser, and an evaporator. The processor determines the amount of a refrigerant in the refrigerant circuit based on a detection result detected by the sensor during operation of the refrigeration cycle apparatus.

A centrifugal chiller includes a first expansion unit (23) that expands refrigerant that has been compressed and condensed, and an evaporation unit (41) that evaporates the expanded refrigerant and supplies the evaporated refrigerant to a compression unit (15). The first expansion unit (23) has an orifice (20) through which refrigerant condensed by a condensation unit (17) passes, and a flow rate regulation valve (22) that can regulate the amount of refrigerant condensed by the condensation unit (17) flowing through and that is connected in parallel with the orifice (20).