A system for measuring and recharging an air conditioning system includes a vent sensor configured to be coupled to an outlet vent of an air conditioning system. The vent sensor is configured to measure at least one parameter of an air flow from the outlet vent. A processor is in signal communication with the vent sensor. The processor is configured to receive the at least one parameter of the air flow and determine a current refrigerant level of the air conditioning system.

An absorption chiller includes a heating medium supply pipe configured to supply a heating medium from a heating medium pipe to a cooling water pipe; a cooling water discharge pipe configured to discharge a cooling water from the cooling water pipe to the heating medium pipe; a control valve provided on the heating medium supply pipe and the cooling water discharge pipe, respectively; and a controller configured to cause the control valve to be opened and to cause the heating medium in the heating medium pipe to be introduced into the cooling water pipe, when a temperature detected by a cooling water temperature detector is equal to or lower than a predetermined temperature, in a wet lay-up state including a state in which a cooling water inlet shut-off valve and a cooling water outlet shut-off valve are closed and the cooling water pipe is filled with the cooling water.

A method for terminating defrosting of an evaporator (104) is disclosed. The evaporator (104) is part of a vapour compression system (100). The vapour compression system (100) further comprises a compressor unit (101), a heat rejecting heat exchanger (102), and an expansion device (103). The compressor unit (101), the heat rejecting heat exchanger (102), the expansion device (103) and the evaporator (104) are arranged in a refrigerant path, and an air flow is flowing across the evaporator (104). When ice is accumulated on the evaporator (104), the vapour compression system (100) operates in a defrosting mode. At least one temperature sensor (305) monitors a temperature T.sub.air, of air leaving the evaporator (104). A rate of change of T.sub.air is monitored and defrosting is terminated when the rate of change of the temperature, T.sub.air, approaches zero.

A system includes a pressure exchanger (PX). The PX is coupled to a motor that controls an operating speed of the PX. The system further includes a first pressure gauge configured to generate first pressure data indicative of a pressure of a fluid of a condenser. A first controller is to generate a first control signal based on the first pressure data. The motor of the PX is configured to adjust the operating speed of the PX based on the first control signal. The system further includes a pump. The system further includes a fluid density sensor for generating fluid density data associated with a first output fluid of the PX. A second controller is to generate a second control signal based on at least the fluid density data. The pump is to adjust an operating speed of the pump based on the second control signal.

A system includes a pressure exchanger (PX). The PX is coupled to a motor that controls an operating speed of the PX. The system further includes a first pressure gauge configured to generate first pressure data indicative of a pressure of a fluid of a condenser. A first controller is to generate a first control signal based on the first pressure data. The motor of the PX is configured to adjust the operating speed of the PX based on the first control signal. The system further includes a pump. The system further includes a fluid density sensor for generating fluid density data associated with a first output fluid of the PX. A second controller is to generate a second control signal based on at least the fluid density data. The pump is to adjust an operating speed of the pump based on the second control signal.

The present disclosure relates to a method for determining an efficiency curve of a chiller that includes operating a chiller over a range of operating capacities, measuring a temperature of water entering the chiller at an initial capacity, measuring a temperature of water exiting the chiller at the initial capacity, measuring a power consumption of the chiller at the initial capacity, calculating an initial efficiency of the chiller at the initial capacity, measuring a plurality of temperatures of water entering the chiller at a plurality of capacities, measuring a plurality of temperatures of water exiting the chiller at each of the plurality of capacities, measuring a plurality of power consumptions at each of the plurality of capacities, calculating a plurality of efficiencies at each of the plurality of capacities, and generating an efficiency curve for the chiller with the initial efficiency and the plurality of efficiencies.

The disclosed technology includes systems and methods for controlling an air conditioning system. The method of controlling the air conditioning system can include receiving air temperature data from an air temperature sensor and determining that the air conditioning system should operate in a reheat mode based on the air temperature being less than a threshold air temperature. The method can include outputting a control signal to a first electronic expansion valve to close and thereby prevent refrigerant to flow through an outdoor condenser coil. The method can also include outputting a control signal to a second electronic expansion valve to open and thereby permit refrigerant to flow through a reheat coil.

Systems and methods are provided and include first and second case controllers for first and second refrigeration cases. The first case controller receives a first air temperature value of the first refrigeration case and communicates the first air temperature value to the second case controller. The second case controller receives a second air temperature value, determine an evaporator saturated suction temperature (SST) value, controls an evaporator pressure regulator based on a comparison of the evaporator SST value with an evaporator SST setpoint, determines an air temperature control value, determines whether the air temperature control value is within a predetermined range of an air temperature setpoint, and adjusts the evaporator SST setpoint in response to the air temperature control value being outside of the predetermined range of the air temperature setpoint.

An HVAC system includes an evaporator, a condenser, a compressor. A first refrigerant path flows through a first expansion valve, first evaporator inlet, within the evaporator, and out of the evaporator through a first evaporator outlet. A second refrigerant path flows through a second expansion valve, a second evaporator inlet, within the evaporator, and out of the evaporator through a second evaporator outlet. Refrigerant flows from the condenser to the first refrigerant path and the second refrigerant path, and from the first refrigerant path and the second refrigerant path to the compressor.

A dynamic method of maintaining a predefined sub-cooling of a refrigerant exiting a condenser by dynamic control of the circulating mass of refrigerant, by transferring the refrigerant into or towards a receiver installed in parallel with the liquid connection between the condenser and the expansion valve, as a function of the difference in temperatures between the condensation temperature of the saturation liquid and the discharge temperature from the condenser.