Abstract: An air conditioning system having a cooling mode and a free-cooling mode is provided. The system includes a refrigeration circuit, two pressure sensors, a controller, and a pump-protection sequence resident on the controller. The refrigeration circuit includes a compressor and a pump. The first pressure sensor is at an inlet of the pump, while the second pressure sensor is at an outlet of the pump. The controller selectively operates in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operates in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump: The pump-protection sequence turns the pump to an off state based at least upon a differential pressure determined by the controller from pressures detected by the first and second pressure sensors.

Abstract: A method is provided for operating a refrigerant vapor compression system, for example an air-cooled chiller or air-cooled condensing unit, at optimal energy efficiency rating. The method includes the steps of: determining the instantaneous values of a plurality of selected operating parameters of the system's refrigeration unit, calculating a desired control parameter set point indicative of an optimal energy efficiency rating for the refrigeration unit as a function of the selected operating parameters, sensing the instantaneous value of the control parameter, comparing the sensed instantaneous value of the control parameter to the calculated control parameter set point, and adjusting the operating speed of the condenser fans associated with the air-cooled condenser of the refrigeration unit in response to that comparison.

Abstract: Embodiments of the invention provide anti-icing systems (201) for drainage channels (203; 205) used to remove water run-off during heat pump evaporator coil defrosting cycles during cold weather conditions. The invention employs impedance heating to obviate heat tracing cable, its associated thermal insulation and any protective mechanical coverings.

Abstract: A reversible cooling/heating system (20) has an in-line accumulator/dryer unit (74). The accumulator/dryer unit has a body having first and second ports (76, 78). A foraminate conduit (82) is positioned at least partially within the body. A desiccant (80) at least partially surrounds a first portion of the conduit. A pressure-actuated valve is located along the conduit.

Abstract: A method is provided for operating a refrigerant vapor compression system, for example an air-cooled chiller or air-cooled condensing unit, at optimal energy efficiency rating. The method includes the steps of: determining the instantaneous values of a plurality of selected operating parameters of the system's refrigeration unit, calculating a desired control parameter set point indicative of an optimal energy efficiency rating for the refrigeration unit as a function of the selected operating parameters, sensing the instantaneous value of the control parameter, comparing the sensed instantaneous value of the control parameter to the calculated control parameter set point, and adjusting the operating speed of the condenser fans associated with the air-cooled condenser of the refrigeration unit in response to that comparison.

Abstract: An air conditioning system having a cooling mode and a free-cooling mode is provided. The system includes a refrigeration circuit, two pressure sensors, a controller, and a pump-protection sequence resident on the controller. The refrigeration circuit includes a compressor and a pump. The first pressure sensor is at an inlet of the pump, while the second pressure sensor is at an outlet of the pump. The controller selectively operates in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operates in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump: The pump-protection sequence turns the pump to an off state based at least upon a differential pressure determined by the controller from pressures detected by the first and second pressure sensors.

Abstract: A method of controlling an air conditioning system having a cooling mode and a free-cooling mode, including activating the air conditioning system; measuring a first temperature of ambient air surrounding a condenser; measuring a second temperature of the working fluid; calculating a difference between the first and second temperatures; and comparing the difference to a predetermined value, wherein if the difference is greater than or equal to the predetermined value the free-cooling mode is activated, and wherein if the difference is less than the predetermined value the cooling mode is activated.

Abstract: A reversible cooling/heating system has an in-line accumulator/dryer unit. The accumulator/dryer unit has a body having first and second ports. A foraminate conduit is positioned at least partially within the body. A desiccant at least partially surrounds a first portion of the conduit.

Abstract: A conduit has a first end and interior and exterior surfaces extending downstream from the first end. A strainer has a first end and a second end. An upstream portion of the strainer is positioned engaging a projection on the interior surface of the conduit to resist downstream shifting of the strainer. A strainer body extends at least partially downstream of the upstream portion. The apparatus may be used as a strainer/coupler and may be used to filter water in a chiller apparatus.

Abstract: A method for optimizing free cooling activation comprising the steps of operating an air conditioning unit in a chiller mode, determining a building load, determining a free cooler maximum available capacity (FreeCapM), and activating a free cooling mode of the air conditioning unit when the free cooler maximum available capacity is greater than or equal to the building load.

Abstract: A reversible cooling/heating system has an in-line accumulator/dryer unit. The accumulator/dryer unit has a body having first and second ports. A foraminate conduit is positioned at least partially within the body. A dessicant at least partially surrounds a first portion of the conduit.

Abstract: A method for optimizing free cooling activation comprising the steps of operating an air conditioning unit in a chiller mode, determining a building load, determining a free cooler maximum available capacity (FreeCapM), and activating a free cooling mode of the air conditioning unit when the free cooler maximum available capacity is greater than or equal to the building load.

Abstract: A conduit has a first end and interior and exterior surfaces extending downstream from the first end. A strainer has a first end and a second end. An upstream portion of the strainer is positioned engaging a projection on the interior surface of the conduit to resist downstream shifting of the strainer. A strainer body extends at least partially downstream of the upstream portion. The apparatus may be used as a strainer/coupler and may be used to filter water in a chiller apparatus.

Abstract: A conduit has a first end and interior and exterior surfaces extending downstream from the first end. A strainer has a first end and a second end. An upstream portion of the strainer is positioned engaging a projection on the interior surface of the conduit to resist downstream shifting of the strainer. A strainer body extends at least partially downstream of the upstream portion. The apparatus may be used as a strainer/coupler and may be used to filter water in a chiller apparatus.

Abstract: A conduit has a first end and interior and exterior surfaces extending downstream from the first end. A strainer has a first end and a second end. An upstream portion of the strainer is positioned engaging a projection on the interior surface of the conduit to resist downstream shifting of the strainer. A strainer body extends at least partially downstream of the upstream portion. The apparatus may be used as a strainer/coupler and may be used to filter water in a chiller apparatus.

Abstract: A control algorithm controls a coil defrosting cycle on a reversible heat pump by storing values representing performance of a clean coil, i.e., one with no frost build-up, and monitoring those values as they evolve over time. The values are used to create a “frost factor” whose value varies between 0%, signifying a clean coil, and 100%, signifying a heavily frosted coil. When the frost factor reaches a predetermined value close to 100%, the refrigerant cycle of the heat pump is inverted (reversed) to achieve coil defrosting.