Heat Exchanger Glide Control in Zeotropic Air Conditioning
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Solution Overview
Problem
Existing air-conditioning apparatuses using zeotropic refrigerant mixtures experience decreased heat exchanging efficiency due to significant differences in temperature glides between refrigerants in different refrigeration cycles, leading to inefficient heat exchange processes.
Innovation Solution
An air-conditioning apparatus is designed with a first and second refrigeration cycle, where zeotropic refrigerant mixtures with different saturated gas and liquid temperatures under the same pressure are used, and the heat exchanger is configured to control the temperature differences between the refrigerants, ensuring they flow counter to each other, with the expansion device adjusting to maintain a predetermined difference between the temperature differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If zeotropic refrigerant mixtures with different temperature glides are used in the first and second refrigeration cycles, then the refrigerants can flow counter to one another in the heat exchanger, but the heat exchanging efficiency decreases due to significant differences in temperature glides
Solution Approach 1:
The patent controls the opening degree of the expansion device to regulate the degree of expansion of the zeotropic refrigerant mixture, thereby adjusting its temperature glide parameter. This parameter change enables the temperature glide of both refrigerants to be maintained within a difference of 10K or less, resolving the contradiction between counter-flow configuration and heat exchanging efficiency by dynamically optimizing the thermal characteristics of the refrigerant mixture
Solution Approach 2:
The patent implements a control mechanism that monitors the temperature differences between the two zeotropic refrigerant mixtures and adjusts the expansion device opening degree accordingly. This feedback control ensures that the temperature glide difference remains within the optimal range, maintaining high heat exchanging efficiency while preserving the benefits of counter-flow heat exchange
2Productivity
If the temperature differences between refrigerants in the heat exchanger are not controlled, then the system operation is simple, but the heat exchanging efficiency decreases
Solution Approach 1:
The patent changes the operational parameters of the zeotropic refrigerant mixture by controlling the expansion device opening degree, which directly affects the temperature glide and temperature difference distribution in the heat exchanger. This parameter control optimizes heat exchanging efficiency without requiring fundamental system redesign
Solution Approach 2:
The patent introduces a dynamic control mechanism where the expansion device opening degree is adjusted based on operating conditions to maintain optimal temperature differences. This dynamic adjustment enables the system to adapt to varying loads and environmental conditions while preserving high heat exchanging efficiency
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, leading to energy savings and improved operational efficiency by minimizing temperature differences in the heat exchanger, enhancing 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
a zeotropic refrigerant mixture including refrigerants having different saturated gas temperatures and saturated liquid temperatures under the same pressure
Implementation Method 4
a difference between the first temperature difference and the second temperature difference is held in a predetermined value or less by controlling an opening degree of the second expansion device
Data Source
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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 15c, 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 15c, 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 16d.