Abstract: A freezer and method of operating a freezer are provided with an adaptive defrost cycle. The freezer includes a controller that operates the freezer to: provide cooling to a cabinet via an evaporator during periodic operational cycles, monitor a time elapsed since a most recent defrost cycle, determine whether the time elapsed is greater than a current defrost interval, and perform a defrost cycle if so. The controller varies the current defrost interval between a first, larger time value and a second, smaller time value based on a plurality of trigger signals in response to various operating characteristics of the freezer monitored by sensors. After each defrost cycle is completed, the current defrost interval is reset to the first, larger time value.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor that is a variable speed compressor, a second expansion device, and an evaporator. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. A controller stages operation of the first and second compressors and runs the second compressor at an initial speed less than a maximum speed initially when a staging protocol is performed during start up or re-starting of the refrigeration system.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor that is a variable speed compressor, a second expansion device, and an evaporator. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. A controller stages operation of the first and second compressors and runs the second compressor at an initial speed less than a maximum speed initially when a staging protocol is performed during start up or re-starting of the refrigeration system.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor that is a variable speed compressor, a second expansion device, and an evaporator. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. A controller stages operation of the first and second compressors and runs the second compressor at an initial speed less than a maximum speed initially when a staging protocol is performed during start up or re-starting of the refrigeration system.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor that is a variable speed compressor, a second expansion device, and an evaporator. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. A controller stages operation of the first and second compressors and runs the second compressor at an initial speed less than a maximum speed initially when a staging protocol is performed during start up or re-starting of the refrigeration system.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor that is a variable speed compressor, a second expansion device, and an evaporator. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. A controller stages operation of the first and second compressors and runs the second compressor at an initial speed less than a maximum speed initially when a staging protocol is performed during start up or re-starting of the refrigeration system.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device that is in fluid communication with the first fluid circuit. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor, a second expansion device, and an evaporator that is in fluid communication with the second fluid circuit. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. At least one of the first or second compressors is a variable speed compressor.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor that is a variable speed compressor, a second expansion device, and an evaporator. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. A controller stages operation of the first and second compressors and runs the second compressor at an initial speed less than a maximum speed initially when a staging protocol is performed during start up or re-starting of the refrigeration system.

Abstract: An ultra low temperature refrigeration system and technique, includes a cabinet with a storage chamber maintained at a certain temperature range, a door providing a seal with the cabinet when engaged with the cabinet, and a dehumidifying unit connected to the cabinet for dehumidifying the storage chamber within the cabinet.

Abstract: A storage cabinet (16) is provided for an ultra-low temperature freezer (10). The cabinet (16) includes a base platform (62a), a plurality of side structural insulated panels (45, 50, 55) each defining a side wall of the storage cabinet (16), and a plurality of generally vertically oriented posts (40) extending from the base platform (62a). Each of the plurality of vertically oriented posts (40) has a slot (40a) for receiving an edge portion (45a, 50a, 55a) of one of the insulated panels (45, 50, 55) therealong. The slot (40a) may have a generally U-shaped profile that surrounds the edge portion (45a, 50a, 55a) of one of the insulated panels (45, 50, 55). At least one of the generally vertically oriented posts (40) has a channel (40c) that extends along a longitudinal dimension thereof, the channel (40c) being configured to receive one of insulation, tubing, or wiring of the freezer therethrough.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device that is in fluid communication with the first fluid circuit. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor, a second expansion device, and an evaporator that is in fluid communication with the second fluid circuit. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. At least one of the first or second compressors is a variable speed compressor.

Abstract: A storage cabinet (16) is provided for an ultra-low temperature freezer (10). The cabinet (16) includes a base platform (62a), a plurality of side structural insulated panels (45, 50, 55) each defining a side wall of the storage cabinet (16), and a plurality of generally vertically oriented posts (40) extending from the base platform (62a). Each of the plurality of vertically oriented posts (40) has a slot (40a) for receiving an edge portion (45a, 50a, 55a) of one of the insulated panels (45, 50, 55) therealong. The slot (40a) may have a generally U-shaped profile that surrounds the edge portion (45a, 50a, 55a) of one of the insulated panels (45, 50, 55). At least one of the generally vertically oriented posts (40) has a channel (40c) that extends along a longitudinal dimension thereof, the channel (40c) being configured to receive one of insulation, tubing, or wiring of the freezer therethrough.

Abstract: A refrigeration system is provided for use with an ultra-low temperature freezer having a deck and a refrigerated cabinet supported above the deck. The system has a first refrigeration stage and a second refrigeration stage. The first stage defines a first fluid circuit for circulating a first refrigerant. The first stage has a first compressor, a condenser and a first expansion device that is in fluid communication with the first fluid circuit. The second stage defines a second fluid circuit for circulating a second refrigerant. The second stage has a second compressor, a second expansion device and an evaporator that is in fluid communication with the second fluid circuit. The system includes an insulated enclosure supported within the deck and a split-flow heat exchanger that is in fluid communication with the first and second fluid circuits and which is located within the insulated enclosure.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device that is in fluid communication with the first fluid circuit. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor, a second expansion device, and an evaporator that is in fluid communication with the second fluid circuit. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. At least one of the first or second compressors is a variable speed compressor.

Abstract: A refrigeration system is provided for use with an ultra-low temperature freezer having a deck and a refrigerated cabinet supported above the deck. The system has a first refrigeration stage and a second refrigeration stage. The first stage defines a first fluid circuit for circulating a first refrigerant. The first stage has a first compressor, a condenser and a first expansion device that is in fluid communication with the first fluid circuit. The second stage defines a second fluid circuit for circulating a second refrigerant. The second stage has a second compressor, a second expansion device and an evaporator that is in fluid communication with the second fluid circuit. The system includes an insulated enclosure supported within the deck and a split-flow heat exchanger that is in fluid communication with the first and second fluid circuits and which is located within the insulated enclosure.

Abstract: A two-stage cascade refrigeration system is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant, and has a first compressor, a condenser, and a first expansion device that is in fluid communication with the first fluid circuit. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant, with the second refrigeration stage having a second compressor, a second expansion device, and an evaporator that is in fluid communication with the second fluid circuit. A heat exchanger is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants. At least one of the first or second compressors is a variable speed compressor.

Abstract: An ultra low temperature refrigeration system and technique, includes a cabinet with a storage chamber maintained at a certain temperature range, a door providing a seal with the cabinet when engaged with the cabinet, and a dehumidifying unit connected to the cabinet for dehumidifying the storage chamber within the cabinet.