Dual-Evaporator Heat Exchange to Eliminate Refrigerant Pump-Down
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Solution Overview
Problem
Conventional refrigerating systems require a 'pump-down' operation to collect remaining refrigerant from evaporators, which can lead to compressor damage, high power consumption, and efficiency degradation, especially when transitioning between cooling and freezing modes.
Innovation Solution
A refrigerating system with a heat exchanging unit that allows for temperature equalization between evaporators, eliminating the need for a 'pump-down' operation by exchanging refrigerant between evaporators, thereby maintaining compressor suction pressure and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a pump-down operation is performed to collect remaining refrigerant from evaporators, then the refrigerant is collected to the compressor, but the compressor suction pressure and discharge pressure are excessively lowered causing compressor damage or loss
Solution Approach 1:
A heat exchanger is introduced as an intermediary device between the evaporators and the compressor. The heat exchanger receives refrigerant from the evaporators and transfers heat to warm the refrigerant before it enters the compressor, preventing excessive pressure drops and protecting the compressor during pump-down operations.
Solution Approach 2:
The system changes the temperature parameter of the refrigerant by using the heat exchanger to warm the refrigerant from evaporators before it reaches the compressor. This parameter change prevents the refrigerant from entering the compressor at excessively low temperatures and pressures, thereby protecting the compressor.
2Quantity of substance
If a pump-down operation is performed to collect remaining refrigerant, then the refrigerant is collected to the compressor, but high power is required operating the compressor, thereby degrading the efficiency of the refrigerating system
Solution Approach 1:
The heat exchanger serves as a mediator that passively warms the refrigerant using heat from other sources, eliminating the need for high-power compressor operation during pump-down. This reduces the energy required for refrigerant collection.
Solution Approach 2:
The system replaces the mechanical compression-based refrigerant collection method with a thermal-based method using the heat exchanger. Instead of relying on compressor suction to pull refrigerant, the heat exchanger uses thermal energy to warm and move refrigerant, reducing mechanical energy consumption.
3Quantity of substance
If a pump-down operation is performed to collect remaining refrigerant, then the refrigerant is collected to the compressor, but the collected refrigerant may backflow to the evaporator due to lowered suction and outlet pressure
Solution Approach 1:
The heat exchanger acts as an intermediary that creates a pressure buffer between the evaporators and the compressor. By warming the refrigerant, it maintains sufficient pressure to prevent backflow to the evaporators while still enabling refrigerant collection.
Solution Approach 2:
The heat exchanger performs preliminary warming of the refrigerant before it reaches the compressor, creating a counteracting effect that prevents the pressure drop from causing backflow. This preliminary action counteracts the harmful backflow effect before it occurs.
4Adaptability or versatility
If multiple evaporators are used to independently cool multiple cooling spaces, then each cooling space can be cooled independently, but the respective evaporators have different outlet temperatures causing refrigerant to remain at evaporators and requiring pump-down operations
Solution Approach 1:
The heat exchanger merges the refrigerant streams from multiple evaporators with different temperatures. By combining and warming these streams, it creates a unified refrigerant flow that can be easily collected by the compressor without requiring complex pump-down operations for each evaporator.
Solution Approach 2:
The heat exchanger serves multiple functions: it warms refrigerant from different evaporators, prevents backflow, and facilitates compressor suction. This single device handles multiple refrigerant management tasks that would otherwise require separate control mechanisms for each evaporator.
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
The system effectively collects remaining refrigerant without additional 'pump-down' operations, enhancing compressor reliability and system efficiency by maintaining consistent suction pressure and reducing power consumption.
Implementation Method 1
a heat exchanging unit for performing heat exchange between the first evaporator and the second evaporator
Data Source
AI summary
A refrigerating system is disclosed. Since heat exchange is performed between first and second evaporators by a heat exchanging unit, the first and second evaporators have temperatures similar to each other, thereby requiring no additional 'pump-down' operation. Also, a compressor does not have a discharge occurrence owing to no additional 'pump-down' operation, thereby having no loss and an enhanced reliability. Besides, since no additional pump-down operation is required, power consumption for operating the compressor so as to collect a remaining refrigerant is reduced. Accordingly, the efficiency of the refrigerating system is enhanced. Furthermore, as the 'pump-down' operation is not required, a backflow preventing unit for preventing a refrigerant collected from an evaporator from backflowing to the evaporator is not required. Accordingly, the fabrication cost is reduced.