Open cycle thermal management system with a vapor pump device and recuperative heat exchanger
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Solution Overview
Problem
Conventional refrigeration systems are heavy and power-consuming due to the need for large compressors and condensers, making them unsuitable for mobile platforms or applications requiring precise temperature control of high heat flux, temperature-sensitive loads.
Innovation Solution
An open-circuit refrigeration system with a vapor pump device, recuperative heat exchanger, and back pressure regulator, which operates without condensers, using a refrigerant fluid like ammonia to efficiently manage thermal energy by maintaining the refrigerant in a two-phase region, reducing system size and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional closed-circuit refrigeration systems are used, then reliable temperature control is achieved, but system weight and power consumption increase significantly
Solution Approach 1:
The patent removes the condenser component from the conventional refrigeration cycle, transitioning to an open-circuit system where refrigerant vapor is discharged directly to the atmosphere after evaporating the coolant. This extraction of the condenser eliminates the need for heavy compression and condensation equipment, significantly reducing system weight while maintaining temperature control through the phase change process
Solution Approach 2:
The system utilizes the phase transition of refrigerant from liquid to vapor in the evaporator to cool the coolant, and then discharges the vapor directly without condensation. This phase change approach provides efficient heat transfer and temperature control while avoiding the need for heavy condensing equipment, resolving the contradiction between reliability and weight
2Reliability
If conventional closed-circuit refrigeration systems are used, then temperature control is maintained, but electrical power consumption increases
Solution Approach 1:
By removing the condenser and transitioning to an open-circuit configuration, the system eliminates the energy-intensive compression and condensation processes. The refrigerant vapor is discharged directly to the atmosphere after performing its cooling function, dramatically reducing electrical power consumption while maintaining effective temperature control through evaporative cooling
Solution Approach 2:
The system leverages the latent heat of vaporization during the refrigerant's phase change from liquid to vapor to provide efficient cooling. This natural phase transition process requires minimal energy input compared to mechanical compression, achieving reliable temperature control with significantly reduced power consumption
3Volume of moving object
If system size is reduced for mobile applications, then mobility is improved, but heat transfer efficiency may deteriorate
Solution Approach 1:
The system utilizes the high heat transfer coefficients associated with phase change processes in the evaporator. The refrigerant's transition from liquid to vapor absorbs large amounts of heat efficiently, maintaining high heat transfer effectiveness in a compact configuration. This phase change mechanism allows the system to achieve excellent heat transfer performance without requiring large component sizes
Solution Approach 2:
The system employs fluid dynamics and phase change flow patterns to maximize heat transfer efficiency in a compact evaporator design. By optimizing the two-phase flow characteristics and utilizing the high thermal conductivity of the refrigerant during phase transition, the system achieves superior heat transfer performance in a reduced volume suitable for mobile applications
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 achieves significant reduction in size and weight while maintaining precise temperature control of high heat flux loads, with improved heat transfer coefficients and reduced power consumption compared to traditional closed-circuit systems.
Implementation Method 1
an evaporator having an evaporator inlet and an evaporator outlet, the evaporator configured to extract heat from a heat load that contacts the evaporator
Implementation Method 2
The recuperative heat exchanger transfers heat energy from the refrigerant fluid at the evaporator outlet to the refrigerant fluid upstream of the expansion valve
Implementation Method 3
The combination of condensers and compressors can add significant amount of weight and can consume relatively large amounts of electrical power
Implementation Method 4
The evaporator operates at a vapor quality of less than or equal to 1.0, and the recuperative heat exchanger evaporates any refrigerant liquid at the evaporator outlet into a vapor
Data Source
AI summary
A thermal management system that includes an open-circuit refrigeration system having an open-circuit refrigerant fluid flow path is described. The open-circuit refrigeration system includes a receiver configured to store a refrigerant fluid, an evaporator configured to receive the refrigerant fluid at a evaporator inlet and to extract heat from a heat load that contacts the evaporator, and provide refrigerant vapor at a evaporator outlet. The open-circuit refrigeration system also includes a vapor pump device having a vapor pump inlet that receives the refrigerant vapor and having a vapor pump outlet that outputs compressed refrigerant vapor to an exhaust line coupled to the vapor pump outlet, with the receiver, the evaporator, the vapor pump device, and the exhaust line connected in the open-circuit refrigerant fluid flow path.