Air-Conditioning System With Phase Change Thermal Storage
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Solution Overview
Problem
Existing air-conditioning systems for large machines face challenges in maintaining operator comfort during idle periods without engine power, as they are inefficient and costly, and previous solutions like storage heat exchangers have limitations in temperature control and scalability.
Innovation Solution
An air-conditioning system comprising a primary circuit with a compressor, condenser, evaporator, and chiller, and a secondary circuit with a phase change material heat exchanger and coolant-to-air heat exchanger, which allows for selective activation based on the machine's operating state to store and utilize thermal energy, enabling continuous cabin cooling without direct engine power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is turned off during idle periods, then fuel consumption and pollution are reduced, but the air-conditioning system shuts off and operator comfort deteriorates
Solution Approach 1:
The system pre-cools the phase change material in the thermal energy storage unit during periods when the engine is running and air-conditioning is needed. This preliminary cooling action stores thermal energy in the PCM, which is then released during idle periods when the engine is off, maintaining operator comfort without fuel consumption.
Solution Approach 2:
The phase change material acts as an intermediary thermal energy storage medium between the air-conditioning system and the cabin environment. It absorbs and releases thermal energy to bridge the gap between engine operation states, maintaining temperature control during transitions.
2Ease of operation
If the engine idles for long periods to power the air-conditioning system, then operator comfort is maintained, but fuel efficiency decreases and environmental impact increases
Solution Approach 1:
The system performs preliminary cooling of the phase change material during engine operation, storing thermal energy in advance. This allows the air-conditioning system to be shut off during idle periods while still maintaining operator comfort through the stored thermal energy, thereby improving fuel efficiency.
Solution Approach 2:
The phase change material serves itself by automatically absorbing and releasing thermal energy based on temperature changes. During engine operation, it absorbs excess heat; during idle periods, it releases stored cooling energy, providing self-regulating temperature control without continuous engine power.
3Duration of action of stationary object
If a storage heat exchanger with phase change material is used, then thermal energy can be stored for later use, but the heat transfer rate and temperature control are limited
Solution Approach 1:
The thermal energy storage system is segmented into multiple phase change material units with different phase change temperatures. This segmentation allows the system to provide both long-duration storage (by utilizing multiple phase transitions) and high heat transfer rates (by having multiple units operating at different temperature levels simultaneously).
Solution Approach 2:
The system uses composite phase change materials with different phase change temperatures to enhance both the duration and rate of thermal energy storage. The composite structure allows for staged heat release, maintaining high heat transfer rates over extended periods as different materials transition at different temperatures.
4Adaptability or versatility
If a storage heat exchanger is used for air-conditioning, then the system can operate without the main air-conditioning loop, but the system size and complexity increase
Solution Approach 1:
The phase change material thermal energy storage units are integrated with the existing air-conditioning system components, merging the storage function with the cooling function. This combination allows the system to operate independently using stored thermal energy while avoiding the need for separate, bulky storage systems.
Solution Approach 2:
The phase change material units serve multiple functions: they act as thermal energy storage media, heat exchangers, and temperature regulation devices all in one component. This multi-functionality reduces overall system complexity while providing the capability to operate independently of the main air-conditioning loop.
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 maintains cabin temperature during idle periods by storing thermal energy in phase change materials, reducing fuel consumption and pollution, and scaling to meet the cooling demands of larger machines.
Implementation Method 1
The secondary circuit includes a heat exchanger, having a phase change material, in fluid communication with the chiller to receive the coolant. The heat exchanger is configured to exchange heat between the phase change material and the coolant and store energy in the phase change material.
Implementation Method 2
The heat exchanger is configured to exchange heat between the phase change material and the coolant
Implementation Method 3
The heat exchanger is configured to exchange heat between the phase change material and the coolant
Implementation Method 4
The secondary circuit further includes a coolant-to-air heat exchanger in fluid communication with the heat exchanger to receive the coolant. The coolant-to-air heat exchanger is configured to exchange heat between the coolant and air in the operator cabin.
Implementation Method 5
The coolant-to-air heat exchanger is configured to exchange heat between the coolant and air in the operator cabin
Implementation Method 6
The primary circuit includes a compressor configured to compress and circulate the refrigerant
Implementation Method 7
The primary circuit also includes a condenser configured to exchange heat between the refrigerant and air in outside environment
Implementation Method 8
The primary circuit also includes a condenser configured to exchange heat between the refrigerant and air in outside environment
Implementation Method 9
The primary circuit also includes an evaporator configured to exchange heat between the refrigerant and air in an operator cabin
Implementation Method 10
The primary circuit also includes an evaporator configured to exchange heat between the refrigerant and air in an operator cabin
Data Source
AI summary
An air-conditioning system including a primary circuit and a secondary circuit is provided. The primary circuit includes a flow of refrigerant, an evaporator and a chiller configured to exchange heat between a coolant and the refrigerant. The secondary circuit includes a heat exchanger in fluid communication with the chiller to receive the coolant. The heat exchanger includes a phase change material in heat exchange relationship with the coolant, such that the coolant exchanges heat with the phase change material to store thermal energy in the phase change material. The air-conditioning system is implemented in a machine in which during an idle-off state, the stored energy in the heat exchanger is discharged to provide an air-conditioning effect.