	US 11,874,035 B2
	Parallel flow expansion for pressure and superheat control
Scott Eric Sloan, Sun Prairie, WI (US); Daniel James Dettmers, McFarland, WI (US); Alan David Stahl, Oregon, WI (US); Walt Bernhard Waetjen, Sun Prairie, WI (US); and Clifford William Calvert, Madison, WI (US)
Assigned to THERMA-STOR LLC, Madison, WI (US)
Filed by Therma-Stor LLC, Madison, WI (US)
Filed on Sep. 2, 2021, as Appl. No. 17/465,626.
Prior Publication US 2023/0064581 A1, Mar. 2, 2023
Int. Cl. F25B 41/385 (2021.01); F25B 41/22 (2021.01); F25B 5/04 (2006.01); F25B 6/04 (2006.01); F25B 49/02 (2006.01)

CPC F25B 41/385 (2021.01) [F25B 5/04 (2013.01); F25B 6/04 (2013.01); F25B 41/22 (2021.01); F25B 49/02 (2013.01); F25B 2600/2505 (2013.01); F25B 2700/2117 (2013.01)]

18 Claims

1. A Heating, Ventilation, and Air Conditioning (HVAC) system, comprising:

a condenser configured to:

receive a refrigerant in a gaseous state;

condense the refrigerant from the gaseous state into a liquid state; and

output a first condensed refrigerant in the liquid state;

a fixed expansion device fluidly coupled to the condenser, the fixed expansion device comprising a tubular structure with an opening that is configured to:

receive the first condensed refrigerant from the condenser;

output a first portion of the first condensed refrigerant at a fixed flow rate, wherein the fixed flow rate is proportional to a diameter of the opening of the tubular structure;

a sensing bulb comprising:

a hollow chamber; and

a capillary tube fluidly coupled to the hollow chamber; and

wherein the sensing bulb is configured to:

sense a temperature of a primary evaporator; and

output a fluid from the hollow chamber via the capillary tube based on the sensed temperature of the primary evaporator;

and

a variable expansion device fluidly coupled to the condenser, wherein

the variable expansion device comprises:

a flexible diaphragm fluidly coupled to the capillary tube of the sensing bulb configured to:

receive the fluid from the sensing bulb; and

apply a first force to a pin based on the received fluid from the sensing bulb;

the pin operably configured to apply a second force to a valve based on the first force, wherein the size of the pin is proportional to a ratio between a maximum variable flow rate of the variable expansion device and a total flow rate that is equal to the fixed flow rate plus the maximum variable flow rate of the variable expansion device; and

the valve is fluidly coupled to the condenser and configured to:

receive the first condensed refrigerant from the condenser;

output a second portion of the first condensed refrigerant at a variable flow rate, wherein the variable flow rate is proportional to the sensed temperature of the evaporator.

11. A method for operating a Heating, Ventilation, and Air Conditioning (HVAC) system, comprising:

receiving, at a fixed expansion device, a refrigerant from a condenser;

receiving, at a variable expansion device, the refrigerant from the condenser;

outputting, by the fixed expansion device, a first portion of the refrigerant to a first downstream HVAC component at a fixed flow rate;

sensing, by a sensing bulb, a temperature of a primary evaporator;

applying a first force to a pin of the variable expansion device based on the sensed temperature, wherein:

applying the first force to the pin repositions the pin within the variable expansion device; and

the size of the pin is proportional to a ratio between a maximum variable flow rate of the variable expansion device and a total flow rate that is equal to the fixed flow rate plus the maximum variable flow rate of the variable expansion device;

applying a second force to a valve of the variable expansion device based on the first force; and

outputting, by the valve of the variable expansion device, a second portion of the refrigerant to a second downstream HVAC component at a variable flow rate based on the second force.

18. A Heating, Ventilation, and Air Conditioning (HVAC) system, comprising:

an evaporator configured to:

receive a refrigerant in a liquid state;

evaporate the refrigerant into a gaseous state; and

output the refrigerant in the gaseous state;

a compressor fluidly coupled to the evaporator, configured to:

receive the refrigerant in the gaseous state;

compress the refrigerant; and

output the compressed refrigerant in the gaseous state;

a condenser fluidly coupled to the compressor, configured to:

receive the compressed refrigerant from the compressor;

condense the compressed refrigerant from the gaseous state into the liquid state; and

output the condensed refrigerant in the liquid state;

a fixed expansion device fluidly coupled to the condenser, comprising a tubular structure with an opening that is configured to:

receive the condensed refrigerant from the condenser;

output a first portion of the condensed refrigerant at a fixed flow rate, wherein the fixed flow rate is proportional to a diameter of the opening of the tubular structure;

a sensing bulb comprising:

a hollow chamber; and

a capillary tube fluidly coupled to the hollow chamber; and

wherein the sensing bulb is configured to:

sense a temperature of the evaporator; and

output a fluid from the hollow chamber via the capillary tube based on the sensed temperature of the evaporator;

and

a variable expansion device fluidly coupled to the condenser, wherein:

the variable expansion device is configured to:

receive the condensed refrigerant from the condenser;

output a second portion of the condensed refrigerant at a variable flow rate, wherein the variable flow rate is proportional to the sensed temperature of the evaporator; and

the variable expansion device comprises:

a flexible diaphragm fluidly coupled to the capillary tube of the sensing bulb, configured to:

receive the fluid from the sensing bulb; and

apply a first force to a pin based on the received fluid from the sensing bulb;

the valve fluidly coupled to the condenser and configured to output the second portion of the condensed refrigerant.