Counter-Flow Heat Exchanger Control for Zeotropic Refrigerants
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Solution Overview
Problem
Existing air-conditioning technologies face inefficiencies in heat exchanging due to the significant difference in temperature glides of zeotropic refrigerant mixtures across different refrigeration cycles, leading to decreased heat exchanging efficiency.
Innovation Solution
An air-conditioning apparatus is designed with a first and second refrigeration cycle, utilizing zeotropic refrigerant mixtures with different saturated gas and liquid temperatures under the same pressure, where the heat exchanger configuration ensures that the refrigerants flow counter to each other, and the expansion device controls the temperature differences to maintain them within a predetermined value, enhancing heat exchanging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If zeotropic refrigerant mixtures with different temperature glides are used in first and second refrigeration cycles, then the refrigeration cycles can operate independently with different refrigerants, but the heat exchanging efficiency decreases due to significant difference in temperature glides
Solution Approach 1:
The invention changes the temperature parameter distribution by controlling the temperature difference between refrigerants at different positions in the heat exchanger. Specifically, it ensures that the temperature difference between the first and second refrigerants is smaller at the high-temperature end than at the low-temperature end, optimizing the temperature glide matching and improving heat exchange efficiency while maintaining the ability to use different zeotropic refrigerant mixtures
Solution Approach 2:
The invention dynamically adjusts the operating conditions of the refrigeration cycles to maintain optimal temperature differences during heat exchange. By controlling the temperature difference distribution along the heat exchanger length, the system adapts to the different temperature glides of various zeotropic refrigerant mixtures, resolving the contradiction between versatility and efficiency
2Loss of energy
If refrigerants flow counter to each other in the heat exchanger, then heat exchanging efficiency is improved, but the temperature glide difference between different zeotropic refrigerant mixtures still causes efficiency loss
Solution Approach 1:
The invention optimizes the temperature parameter distribution in the counter-flow heat exchanger by ensuring that the temperature difference between refrigerants is smaller at the high-temperature end and larger at the low-temperature end. This parameter optimization allows the system to maintain high heat exchange efficiency while being compatible with different zeotropic refrigerant mixtures having different temperature glides
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 configuration increases heat exchanging efficiency between the refrigerants, resulting in energy savings by optimizing the temperature differences within the heat exchanger, thereby improving the overall performance of the air-conditioning system.
Implementation Method 1
Heat of the first refrigerant and heat of the second refrigerant are exchanged by the heat exchanger for heating
Implementation Method 2
the first refrigerant which is supplied to the first passage of the heat exchanger for heating and the second refrigerant which is supplied to the second passage flow counter to one another
Implementation Method 3
controlling an opening degree of the second expansion device so that a difference between the first temperature difference and a second temperature difference is a predetermined value or less
Data Source
AI summary
When a first temperature difference is the difference between an inlet temperature of a first refrigerant and an outlet temperature of the first refrigerant in the heat exchanger for heating, and a second temperature difference is the difference between an inlet temperature of a second refrigerant and an outlet temperature of the second refrigerant in the heat exchanger for heating, the difference between the first temperature difference and the second temperature difference is held in a predetermined value or less by controlling the opening degree of a second expansion device.