Thermal management systems for extended operation
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Solution Overview
Problem
Conventional refrigeration systems are heavy and power-intensive, making them unsuitable for mobile platforms and requiring significant power to cool high heat loads while maintaining precise temperature control, especially for temperature-sensitive components.
Innovation Solution
A thermal management system integrating a closed-circuit refrigeration system with a vapor cycle and liquid pumping system, utilizing a phase change material for thermal energy storage, which allows for efficient cooling of high heat loads without the need for large compressors and condensers, and includes an open-circuit refrigeration system to extend cooling capabilities when the stored energy is depleted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional closed-circuit refrigeration systems are used to cool high heat loads, then cooling capacity is achieved, but system weight and power consumption increase significantly
Solution Approach 1:
The system pre-cools phase change material (PCM) during periods of low heat load to store thermal energy, which is then utilized during high heat load periods. This preliminary cooling action eliminates the need for continuously operating heavy compressors and condensers, thereby reducing system weight while maintaining adequate cooling capacity.
Solution Approach 2:
The invention utilizes phase change material (PCM) that absorbs and releases thermal energy during phase transitions (solid-liquid). This phase change mechanism provides high-density thermal energy storage, enabling the system to handle high heat loads without requiring proportionally larger compressors and heat exchangers, thus reducing overall system weight.
2Power
If conventional refrigeration systems are designed to handle large heat loads, then cooling capacity is sufficient, but the systems consume large amounts of electrical power
Solution Approach 1:
The system performs preliminary cooling of PCM during low-demand periods, storing thermal energy that can be released during high-demand periods. This shifts the energy consumption pattern, allowing the compressor to operate at lower power levels or intermittently rather than continuously at high power, thereby reducing overall electrical power consumption while maintaining adequate cooling capacity.
Solution Approach 2:
The phase change material stores large amounts of thermal energy during phase transitions, enabling the system to meet high heat load demands without proportionally increasing compressor power. The PCM acts as a thermal buffer, reducing the peak power requirements and average power consumption of the refrigeration system.
3Ease of operation
If conventional refrigeration systems are used for mobile platforms, then cooling function is provided, but the systems are too heavy and power-intensive
Solution Approach 1:
The system pre-charges the PCM thermal energy storage during periods of low or no heat load, which are typical in mobile applications with intermittent cooling demands. This preliminary action allows the compressor to be smaller and less powerful, making the overall system lighter and more suitable for mobile platforms while still providing adequate cooling function when needed.
Solution Approach 2:
The phase change material provides high-density thermal energy storage in a compact form factor, enabling effective cooling function for mobile platforms without the weight penalty of conventional continuously-operating refrigeration systems. The PCM's latent heat storage capability allows for reduced compressor and heat exchanger sizing, directly reducing system weight.
4Reliability
If conventional refrigeration systems maintain precise temperature control for temperature-sensitive components, then temperature stability is achieved, but system complexity and power consumption increase
Solution Approach 1:
The phase change material maintains a relatively constant temperature during the phase transition process, providing inherent temperature stability for temperature-sensitive components. This natural thermal buffering effect achieves precise temperature control without requiring complex control systems, multiple sensors, or additional active components, thereby reducing system complexity while maintaining reliability.
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 reduces the overall size and weight of refrigeration systems, efficiently extracts heat energy from high heat loads, and maintains precise temperature control without significant power consumption, making it suitable for mobile platforms and temperature-sensitive components.
Implementation Method 1
a thermal energy storage (TES) that stores a phase change material (PCM), with the TES having a TES inlet and a TES outlet fluidly coupled to the liquid separator inlet
Implementation Method 2
causing cooling energy from the refrigerant fluid to be stored in the PCM in latent heat form
Implementation Method 3
The evaporator is configured to extract heat from a heat load that is in thermal conductive or convective contact or in proximity to the evaporator to transfer heat from the heat load to the refrigerant fluid
Implementation Method 4
the compressor induces refrigerant vapor from the vapor side outlet of the liquid separator at a low pressure and compresses the refrigerant vapor at the low pressure into a refrigerant vapor at a high pressure
Implementation Method 5
a heat rejection heat exchanger (i.e., a condenser)
Implementation Method 6
the expansion valve is configured to control a vapor quality of the refrigerant fluid at the evaporator outlet
Data Source
AI summary
A thermal management system includes a closed-circuit refrigeration system that includes a vapor cycle system (VCS) and a liquid pumping system (LPS). The VCS includes a receiver that stores a refrigerant fluid and a liquid separator. The vapor cycle system is configured to operate in one or more operational modes including at least one of a TES cooling mode, a heat load cooling mode, or a pump-down mode. The LPS includes a thermal energy storage (TES) that stores a phase change material (PCM) and a pump fluidly coupled to at least one evaporator. The evaporator is configured to extract heat from a heat load that is in thermal conductive or convective contact to the evaporator to transfer heat to the refrigerant fluid and provide the refrigerant fluid from an evaporator outlet to the TES.