# US 10,119,729 B2 · Evaporator liquid preheater for reducing refrigerant charge

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- Number: US 10,119,729 B2
- Document ID: US10119729B2
- Status: Granted
- Kind: B2
- Application number: 14/789,910
- Filed: 2015-07-01
- Published: 2016-06-23
- Granted: 2018-11-06
- Earliest claimed: 2014-07-01
- Assignees: Evapco, Inc.
- Applicants: Evapco, Inc.
- Inventors: Greg Derosier
- Web page: https://patentgrep.com/patent/US10119729B2

## CPC

- F25B 5/04: arranged in series
- F25B 6/04: arranged in series
- F25B 39/02: Evaporators
- F25B 40/00: Subcoolers, desuperheaters or superheaters
- F25B 41/00: Fluid-circulation arrangements
- F25B 49/02: for compression type machines, plants or systems
- F25B 5/02: arranged in parallel
- F25B 2339/047: Water-cooled condensers
- F25B 2400/05: Compression system with heat exchange between particular parts of the system
- F25B 2400/23: Separators
- F25B 2400/25: Liquid pumps
- F25B 2500/19: Calculation of parameters
- F25B 2700/1933: Suction pressures
- F25B 2700/197: of the evaporator
- F25B 2700/21151: at the suction side of the compressor
- F25B 2700/21175: of the refrigerant at the outlet of the evaporator
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS

## Abstract

A system and method for reducing the refrigerant charge in a refrigeration system by preheating the liquid refrigerant before it is introduced to the evaporator inlet. When refrigerant liquid is introduced to the evaporator inlet, a portion of the refrigerant liquid vaporizes. This refrigerant vapor displaces refrigerant liquid at the inlet of the evaporator. As more refrigerant vapor is introduced, the amount of liquid inside the evaporator is reduced. A heat exchanger is placed before the liquid refrigerant inlet of the evaporator to generate more vapor when the refrigerant enters the evaporator.

## Claims

### Claim 1

A liquid overfeed refrigeration system comprising:
a refrigerant evaporator, a refrigerant compressor, a refrigerant condenser,
an expansion device, and a refrigerant pre-heater situated upstream of the inlet of the refrigerant evaporator, said refrigerant evaporator, refrigerant compressor, refrigerant condenser, expansion device and refrigerant pre-heater connected in a refrigerant flow path in the refrigeration system in the following order: 1) compressor—2) condenser—3) pre-heater—4) expansion device—5) evaporator—1) compressor, said refrigerant flow path also including
a first sensor located between an outlet of the refrigerant evaporator and an inlet of the compressor to measure at least one of temperature, pressure and liquid vapor ratio of refrigerant leaving the refrigerant evaporator,
and a preheater control system configured to control an amount of heat that is applied to refrigerant flowing through said refrigerant pre-heater to said refrigerant evaporator based on data received from said first sensor.

### Claim 2 (depends on 1)

The refrigeration system according to claim 1, wherein said refrigerant pre-heater is a heat exchanger.

### Claim 3 (depends on 2)

The refrigeration system according to claim 2, wherein a heat source for said preheater heat exchanger is warmed refrigerant liquid from said refrigerant condenser.

### Claim 4 (depends on 1)

The refrigeration system according to claim 1, further comprising a separator element configured to separate liquid and vapor refrigerant leaving said evaporator.

### Claim 5 (depends on 1)

The refrigeration system according to claim 1, further comprising an evaporator feed pump located in said refrigerant flow path upstream of between an outlet of the condenser and an inlet of the evaporator.

### Claim 6 (depends on 1)

The refrigeration system according to claim 1, further comprising a defrost system.