Cooling system
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Solution Overview
Problem
Existing commercial refrigeration systems face efficiency and cost issues when low temperature loads are shut off or removed, leading to insufficient refrigerant heating, which can cause the medium temperature compressor to foam and shut down, and current solutions like hot gas dump valves decrease efficiency and increase costs.
Innovation Solution
The use of a heat exchanger to transfer heat from the medium temperature compressor's discharge to the intake, bypassing the need for a hot gas dump valve by directing heated flash gas to the medium temperature compressor, thereby increasing superheat and preventing foaming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hot gas dump valve is used to increase superheat at the medium temperature compressor intake, then the compressor can operate without foaming, but the system efficiency decreases and cost increases
Solution Approach 1:
A heat exchanger is introduced as an intermediary device between the medium temperature compressor discharge and the flash tank. The heat exchanger transfers heat from the hot compressor discharge to the flash gas, heating the flash gas without directly recirculating compressed refrigerant. This mediator approach achieves the superheat increase goal while avoiding the energy loss of re-compression.
Solution Approach 2:
The invention extracts the heating function from the hot gas dump valve system and separates it into a dedicated heat exchanger component. By taking out the heat transfer function from the direct refrigerant recirculation path, the system can achieve the necessary superheat increase without the harmful side effect of re-compressing already compressed refrigerant, thus maintaining efficiency.
2Reliability
If a hot gas dump valve is installed to prevent compressor foaming, then compressor reliability improves, but device complexity and cost increase
Solution Approach 1:
The heat exchanger serves multiple functions: it acts as a condenser for the hot compressor discharge, a heater for the flash gas, and indirectly provides the superheat increase needed for stable compressor operation. By making this single component multi-functional, the system avoids adding a dedicated hot gas dump valve while still achieving the reliability improvement.
3Adaptability or versatility
If refrigerant from low temperature section is insufficient, then the system can operate without freezers, but the medium temperature compressor receives too cool refrigerant causing foaming
Solution Approach 1:
The system performs preliminary heating of the flash gas in the heat exchanger before the refrigerant enters the medium temperature compressor. This advance heating action ensures that even when low temperature section refrigerant is insufficient, the flash gas is pre-heated to the appropriate temperature, preventing foaming and maintaining reliable compressor operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the medium temperature compressor's efficiency by maintaining operation without foaming and reduces system costs by eliminating the need for expensive hot gas dump valves.
Implementation Method 1
The heat exchanger receives hot refrigerant discharged by the medium temperature compressor and a flash gas discharged by a flash tank. The heat exchanger transfers heat from the refrigerant from the medium temperature compressor to the flash gas.
Implementation Method 2
The heat exchanger then directs the flash gas to the intake of the medium temperature compressor to increase the superheat of the refrigerant in the medium temperature compressor.
Data Source
AI summary
An apparatus includes a high side heat exchanger, a flash tank, a load, a compressor, and a heat exchanger. The high side heat exchanger removes heat from a refrigerant. The flash tank stores the refrigerant from the high side heat exchanger and to discharge a flash gas. The load uses the refrigerant from the cool a space proximate the load. The compressor compresses the refrigerant from the load. The heat exchanger transfers heat from the refrigerant from the compressor to the flash gas before the refrigerant from the compressor reaches the high side heat exchanger. The heat exchanger directs the flash gas to the compressor after heat from the refrigerant from the compressor is transferred to the flash gas and directs the refrigerant from the compressor to the high side heat exchanger after heat from the refrigerant from the compressor is transferred to the flash gas.