Resumes
Resumes
Shitong Zha Phones & Addresses
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Snellville, GA
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Lawrenceville, GA
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205 Thorn Berry Way, Conyers, GA 30094
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Woodstock, GA
Publications
Us Patents
Modular Co2 Refrigeration System
View pageUS Patent:
20100031697, Feb 11, 2010
Filed:
Aug 7, 2008
Appl. No.:
12/187957
Inventors:
David K. Hinde - Atlanta GA, US
Lin Lan - Loganville GA, US
Shitong Zha - Conyers GA, US
J. Scott Martin - Conyers GA, US
John M. Gallaher - Atlanta GA, US
Lin Lan - Loganville GA, US
Shitong Zha - Conyers GA, US
J. Scott Martin - Conyers GA, US
John M. Gallaher - Atlanta GA, US
International Classification:
F25B 1/00
F25B 27/00
F25B 27/00
US Classification:
62498, 62513
Abstract:
A cascade CO2 refrigeration system includes a medium temperature loop for circulating a medium refrigerant and a low temperature loop for circulating a CO2 refrigerant. The medium temperature loop includes a heat exchanger having a first side and a second side. The first side evaporates the medium temperature refrigerant. The low temperature loop includes a discharge header for circulating the CO2 refrigerant through the second side of the heat exchanger to condense the CO2 refrigerant, a liquid-vapor separator collects liquid CO2 refrigerant and directs vapor CO2 refrigerant to the second side of the heat exchanger. A liquid CO2 supply header receives liquid CO2 refrigerant from the liquid-vapor separator. Medium temperature loads receive liquid CO2 refrigerant from the liquid supply header for use as a liquid coolant at a medium temperature. An expansion device expands liquid CO2 refrigerant from the liquid supply header into a low temperature liquid-vapor mixture for use by the low temperature loads.
Cascade Refrigeration System With Modular Ammonia Chiller Units
View pageUS Patent:
20120117996, May 17, 2012
Filed:
Nov 17, 2010
Appl. No.:
12/948442
Inventors:
David K. Hinde - Atlanta GA, US
John D. Bittner - Bethlehem GA, US
Shitong Zha - Conyers GA, US
Joseph R. Poland - Decatur GA, US
John D. Bittner - Bethlehem GA, US
Shitong Zha - Conyers GA, US
Joseph R. Poland - Decatur GA, US
International Classification:
F25B 31/00
F25B 41/04
F25D 17/02
F25B 1/00
F25B 43/02
F25B 41/04
F25D 17/02
F25B 1/00
F25B 43/02
US Classification:
62192, 62335, 62498, 62468, 62434, 62216
Abstract:
A cascade refrigeration system includes an upper portion having at least one modular chiller unit that provides cooling to at least one of a low temperature subsystem having a plurality of low temperature loads, and a medium temperature subsystem having a plurality of medium temperature loads. The modular chiller unit includes a refrigerant circuit having at least a compressor, a condenser, an expansion device, and an evaporator. An ammonia refrigerant mixed with a soluble oil circulates within the refrigerant circuit. A control device may be programmed to modulate the position of the expansion device so that a superheat temperature of the ammonia refrigerant near an outlet of the evaporator fluctuates within a substantially predetermined superheat temperature range to positively return soluble oil from the evaporator to the compressor.
Cascade Refrigeration System With Modular Ammonia Chiller Units
View pageUS Patent:
20130091891, Apr 18, 2013
Filed:
Dec 5, 2012
Appl. No.:
13/706122
Inventors:
Hill Phoenix, Inc. - Conyers GA, US
John D. Bittner - Bethlehem GA, US
Shitong Zha - Conyers GA, US
John D. Bittner - Bethlehem GA, US
Shitong Zha - Conyers GA, US
Assignee:
Hill Phoenix, Inc. - Conyers GA
International Classification:
F25B 43/02
US Classification:
62470
Abstract:
A cascade refrigeration system including an upper portion having at least one modular chiller unit that provides cooling to at least one of a low temperature subsystem having a plurality of low temperature loads, and a medium temperature subsystem having a plurality of medium temperature loads. The modular chiller unit includes a refrigerant circuit having at least a compressor, a condenser, an expansion device, and an evaporator. An ammonia refrigerant which may have entrained oil from the compressor circulates within the refrigerant circuit. An oil recycling circuit removes some oil from the ammonia refrigerant for return to the compressor. An oil pot collects oil accumulated in the evaporator and an oil return line drains oil from the oil pot to an ammonia accumulator or directly to the compressor.
Cooling System With Flexible Evaporating Temperature
View pageUS Patent:
20220228780, Jul 21, 2022
Filed:
Apr 5, 2022
Appl. No.:
17/713968
Inventors:
- Stone Mountain GA, US
Shitong Zha - Snellville GA, US
Shitong Zha - Snellville GA, US
International Classification:
F25B 1/10
F25B 41/20
F25B 41/40
F25B 41/20
F25B 41/40
Abstract:
A cooling system implements various processes to improve efficiency in high ambient temperatures. First, the system can flood one or more low side heat exchangers in the system. Second, the system can direct a portion of vapor refrigerant from a low side heat exchanger to a flash tank rather than to a compressor. Third, the system can transfer heat from refrigerant at a compressor suction to refrigerant at the discharge of a high side heat exchanger.
Cooling System With Vertical Alignment
View pageUS Patent:
20210404717, Dec 30, 2021
Filed:
Sep 10, 2021
Appl. No.:
17/471517
Inventors:
- Stone Mountain GA, US
Shitong Zha - Snellville GA, US
Shitong Zha - Snellville GA, US
International Classification:
F25B 41/40
F25B 41/20
F25B 1/00
F25B 49/02
F25B 41/20
F25B 1/00
F25B 49/02
Abstract:
A cooling system uses P-traps to address the oil return issues that result from a vertical separation between the compressor and the high side heat exchanger. Generally, the vertical piping that carries the refrigerant from the compressor to the high side heat exchanger includes P-traps installed at various heights to capture oil in the refrigerant and to prevent that oil from flowing back to the compressor. As oil collects in the P-traps, the refrigerant begins to push the oil upwards until the oil reaches the high side heat exchanger. Multiple piping of different sizes may be used depending on a discharge pressure of the compressor. When the discharge pressure is higher, a larger piping may be used direct the oil and refrigerant to the high side heat exchanger.
Cooling System With Compressor Bypass
View pageUS Patent:
20210404721, Dec 30, 2021
Filed:
Sep 10, 2021
Appl. No.:
17/471422
Inventors:
- Stone Mountain GA, US
Shitong Zha - Snellville GA, US
Shitong Zha - Snellville GA, US
International Classification:
F25B 49/02
F24F 11/46
F25B 41/22
F25B 1/10
F24F 11/46
F25B 41/22
F25B 1/10
Abstract:
A cooling system is designed to generally allow for one or more compressors to be bypassed when ambient temperatures are low. The system includes a bypass line and valve that opens when ambient temperatures are low and/or when the pressure of the refrigerant in the system is low. In this manner, the refrigerant can flow through the bypass line instead of through one or more compressors. These compressors may then be shut off. To supply any needed pressure to cycle the refrigerant, the system may include a pump that turns on when the bypass line is open. When ambient temperatures are extremely low, thermosiphon may be used to cycle the refrigerant.
Cooling System
View pageUS Patent:
20210333030, Oct 28, 2021
Filed:
Jul 8, 2021
Appl. No.:
17/370558
Inventors:
- Stone Mountain GA, US
Shitong Zha - Snellville GA, US
Shitong Zha - Snellville GA, US
International Classification:
F25B 49/02
F25B 9/00
F25B 31/00
F25B 40/04
F25B 9/00
F25B 31/00
F25B 40/04
Abstract:
An apparatus includes a high side heat exchanger, a heat exchanger, a flash tank, a first expansion valve, a second expansion valve, a load, a first compressor, and a second compressor. During a first mode of operation, the second expansion valve directs refrigerant from the flash tank to the load. The refrigerant from the load bypasses the first compressor. The heat exchanger transfers heat from the refrigerant from the high side heat exchanger to the refrigerant from the load. The second compressor compresses the refrigerant from the heat exchanger. During a second mode of operation, the first expansion valve directs refrigerant from the flash tank to the load. The first compressor compresses the refrigerant from the load and the second compressor compresses the refrigerant from the first compressor before the refrigerant from the first compressor reaches the high side heat exchanger.
Cooling System With Oil Return To Accumulator
View pageUS Patent:
20210270505, Sep 2, 2021
Filed:
Feb 27, 2020
Appl. No.:
16/803306
Inventors:
- Stone Mountain GA, US
Shitong Zha - Snellville GA, US
Shitong Zha - Snellville GA, US
International Classification:
F25B 43/02
F25B 41/04
F25B 43/00
F25B 41/04
F25B 43/00
Abstract:
A cooling system drains oil from low side heat exchangers to vessels and then uses compressed refrigerant to push the oil in the vessels back towards a compressor. Generally, the cooling system operates in three different modes of operation: a normal mode, an oil drain mode, and an oil return mode. During the normal mode, a primary refrigerant is cycled to cool one or more secondary refrigerants. As the primary refrigerant is cycled, oil from a compressor may mix with the primary refrigerant and become stuck in a low side heat exchanger. During the oil drain mode, the oil in the low side heat exchanger is allowed to drain into a vessel. During the oil return mode, compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor.