Heat-Recovery Refrigeration Mode Switching by Liquid Pipe Temperature
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Solution Overview
Problem
In heat-recovery-type refrigeration apparatuses, there is a challenge in maintaining operating efficiency when the air-cooling and air-heating loads are balanced, as the high refrigerant flow rate through heat-source-side heat exchangers leads to decreased efficiency, and timely switching between operation modes is necessary to adapt to changes in load distribution.
Innovation Solution
Incorporating a liquid pipe heat exchanger that compares the temperatures of refrigerant on both sides to determine the evaporation-switch liquid pipe temperature condition, allowing for appropriate switching between operation modes where one heat-source-side heat exchanger functions as a radiator and the other as an evaporator, and vice versa, based on the evaporation and radiation loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If either one of the heat-source-side heat exchangers is caused to function as a radiator while the other functions as an evaporator during simultaneous cooling/heating operation, then heat recovery between heat-source-side heat exchangers can be achieved, but the refrigerant flow rate becomes high and operating efficiency decreases when the overall heat load is small
Solution Approach 1:
The system dynamically switches between two operational modes based on the balance between air-cooling load and air-heating load. When loads are balanced, the system switches to a mode where both heat-source-side heat exchangers function as evaporators, reducing refrigerant flow rate and improving operating efficiency. When loads are unbalanced, the system operates in heat recovery mode with one evaporator and one radiator, maximizing heat recovery efficiency.
Solution Approach 2:
The control device changes the operational parameters of the heat-source-side heat exchangers based on load conditions. By monitoring the balance between air-cooling and air-heating loads, the system adjusts whether heat exchangers function as evaporators or radiators, and accordingly adjusts refrigerant flow distribution to optimize between heat recovery and operating efficiency.
2Loss of energy
If the system operates in heat recovery mode with balanced evaporation and radiation loads on heat-source-side heat exchangers, then heat recovery is maximized, but timely switching to a mode where both heat exchangers function as evaporators is delayed, further reducing operating efficiency
Solution Approach 1:
The control device continuously monitors the balance between air-cooling load and air-heating load, and uses this feedback to determine when to switch operational modes. By detecting the load balance state in real-time, the system can timely switch from heat recovery mode to dual-evaporator mode, preventing excessive loss of operating efficiency while maximizing heat recovery during appropriate periods.
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 approach enables timely and efficient switching between operation modes, reducing the decrease in operating efficiency by accurately determining the load balance and adjusting the operation accordingly, thus optimizing the refrigeration process.
Implementation Method 1
a liquid pipe heat exchanger for performing heat exchange with the refrigerant flowing through liquid sides of the plurality of heat-source-side heat exchangers
Implementation Method 2
heat-source-side heat exchangers that can be individually switched between functioning as an evaporator or a radiator of a refrigerant
Implementation Method 3
heat-source-side heat exchangers that can be individually switched between functioning as an evaporator or a radiator of a refrigerant
Data Source
AI summary
In a refrigeration apparatus, in a first operation mode, a comparison is made between a first liquid pipe temperature, which is a temperature of a refrigerant on a side of a liquid pipe heat exchanger that is near usage-side heat exchangers, and a second liquid pipe temperature, which is a temperature of the refrigerant on a side of the liquid pipe heat exchanger that is near a plurality of heat-source-side heat exchangers, the liquid pipe heat exchanger performing heat exchange with the refrigerant flowing through liquid sides of the heat-source-side heat exchangers. When an evaporation-switch liquid pipe temperature condition is satisfied, the heat-source-side heat exchanger functioning as a radiator of the refrigerant is switched to an evaporator of the refrigerant, and the first operation mode is switched to a second operation mode in which the plurality of heat-source-side heat exchangers are caused to function as evaporators of the refrigerant.