Air conditioner units and methods for operating air conditioner units are provided. A method includes determining a steady state speed of a blower fan of the air conditioner unit. The method further includes receiving a call for heating and activating the blower fan in response to the call for heating. The method further includes measuring a speed of the blower fan after activating the blower fan and comparing the measured speed of the blower fan to the steady state speed of the blower fan. When the measured speed of the blower fan is greater than the steady state speed of the blower fan, the method includes disabling one of a plurality of heater banks of a heating unit of the air conditioner unit.

A control method for an air conditioning system includes: calculating an average heat exchange amount of a coil according to real-time operation information; setting a full-load air volume parameter and a full-load water volume parameter in a heat exchange model according to the real-time operation information and the heat exchange model, and calculating a full-load heat exchange amount; calculating a dynamic margin value based on the average heat exchange amount and the full-load heat exchange amount; determining whether the dynamic margin value is greater than a first preset condition or less than a second preset condition, so that the controller outputs a first control signal or a second control signal respectively to adjust a coil water inlet temperature; and when the dynamic margin value is less than the first preset condition and greater than the second preset condition, maintaining the current setting state.

A control method for an air conditioning system includes: calculating an average heat exchange amount of a coil according to real-time operation information; setting a full-load air volume parameter and a full-load water volume parameter in a heat exchange model according to the real-time operation information and the heat exchange model, and calculating a full-load heat exchange amount; calculating a dynamic margin value based on the average heat exchange amount and the full-load heat exchange amount; determining whether the dynamic margin value is greater than a first preset condition or less than a second preset condition, so that the controller outputs a first control signal or a second control signal respectively to adjust a coil water inlet temperature; and when the dynamic margin value is less than the first preset condition and greater than the second preset condition, maintaining the current setting state.

It is provided a refrigeration apparatus that uses liquid fluid as a heat source and is highly reliably configured to reduce the occurrence of dew condensation and freezing at a utilization unit during cooling operation in which a liquid fluid heat exchanger in a heat source unit functions as a radiator. An air conditioner (10) includes a heat source unit (100) having a compressor (110), a first heat exchanger (140) configured to cause heat exchange between a refrigerant and liquid fluid, a second heat exchanger (160) configured to cause heat exchange between the refrigerant and air, and a valve (162) configured to switch to supply or not to supply the second heat exchanger with the refrigerant, a utilization unit (300) constituting a refrigerant circuit (50) along with the heat source unit, and a controller (406) configured to control to operate the compressor and to open or close the valve (162). The controller opens the valve (162) to supply the second heat exchanger with the refrigerant to cause the second heat exchanger to function as a heat absorber when assessing that the refrigerant sent to the utilization unit needs to be decreased in quantity during cooling operation in which the first heat exchanger functions as a radiator.

It is provided a refrigeration apparatus that uses liquid fluid as a heat source and is highly reliably configured to reduce the occurrence of dew condensation and freezing at a utilization unit during cooling operation in which a liquid fluid heat exchanger in a heat source unit functions as a radiator. An air conditioner (10) includes a heat source unit (100) having a compressor (110), a first heat exchanger (140) configured to cause heat exchange between a refrigerant and liquid fluid, a second heat exchanger (160) configured to cause heat exchange between the refrigerant and air, and a valve (162) configured to switch to supply or not to supply the second heat exchanger with the refrigerant, a utilization unit (300) constituting a refrigerant circuit (50) along with the heat source unit, and a controller (406) configured to control to operate the compressor and to open or close the valve (162). The controller opens the valve (162) to supply the second heat exchanger with the refrigerant to cause the second heat exchanger to function as a heat absorber when assessing that the refrigerant sent to the utilization unit needs to be decreased in quantity during cooling operation in which the first heat exchanger functions as a radiator.

Air conditioner units and methods for operating air conditioner units are provided. A method includes determining a steady state speed of a blower fan of the air conditioner unit. The method further includes receiving a call for heating and activating the blower fan in response to the call for heating. The method further includes measuring a speed of the blower fan after activating the blower fan and comparing the measured speed of the blower fan to the steady state speed of the blower fan. When the measured speed of the blower fan is greater than the steady state speed of the blower fan, the method includes disabling one of a plurality of heater banks of a heating unit of the air conditioner unit.

Air conditioner units and methods for operating air conditioner units are provided. A method includes determining a steady state speed of a blower fan of the air conditioner unit. The method further includes receiving a call for heating and activating the blower fan in response to the call for heating. The method further includes measuring a speed of the blower fan after activating the blower fan and comparing the measured speed of the blower fan to the steady state speed of the blower fan. When the measured speed of the blower fan is greater than the steady state speed of the blower fan, the method includes disabling one of a plurality of heater banks of a heating unit of the air conditioner unit.

Control systems are provided that provide thermodynamically decoupled control of temperature and relative humidity and/or reduce or prevent frost formation or remove previously-formed frost. The control systems herein may be included as a component of a heating, ventilation, air conditioning, and refrigeration system that includes a heat exchanger.

An air conditioning system suppresses energy consumption by efficient shared use of air in a common space that is not subjected to air conditioning in an indoor area, among a plurality of air conditioners for the purpose of heat exchange. A plurality of air conditioners each include: a usage-side heat exchanger configured to carry out heat exchange with air in an air-conditioning target space; a heat source-side heat exchanger configured to carry out heat transfer to and from the usage-side heat exchanger; and a heat source-side fan configured to feed air from a common space to the heat source-side heat exchanger and to blow the air into the common space. The heat source-side heat exchangers of the air conditioners are disposed in the common space. A first ventilation fan whose airflow volume is changeable is disposed near an exhaust port through which air is discharged from the common space toward an outdoor area. A controller changes the airflow volume of the ventilation fan, based on information on an air temperature of the common space.

An air conditioning system reduces energy consumption by efficient shared use of air in a common space that is not subjected to air conditioning in an indoor area, among a plurality of air conditioners for the purpose of heat exchange. A plurality of air conditioners each include: an air-conditioning target space-side heat exchanger configured to carry out heat exchange with air in an air-conditioning target space; a common space-side heat exchanger configured to carry out heat transfer to and from the air-conditioning target space-side heat exchanger; and a common space-side fan configured to feed taken in air from the common space to the common space-side heat exchanger and to blow the air into the common space. The common space-side heat exchangers of the air conditioners are disposed in the common space. The air conditioners are controlled based on temperature information items at plural positions in the common space.