Heat pump cascade and method for heating or cooling coolant by using heat pump cascade
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Solution Overview
Problem
Caloric heat pumps face limitations in achieving a high temperature range due to the low temperature swing of caloric materials, which is insufficient for heating and cooling applications in motor vehicles and thermal management of batteries and electronics.
Innovation Solution
A heat pump cascade comprising multiple stages, where each stage has a heat pump with a coolant inlet, a first coolant outlet, and a second coolant outlet, with a volume flow divider that splits the coolant flow between a hot side and a cold side, and a return line connecting the second coolant outlet of subsequent stages to the coolant inlet of preceding stages, enhancing the temperature range and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single-stage heat pump with caloric materials is used, then the device complexity is low, but the temperature lift is insufficient for vehicle heating and cooling applications
Solution Approach 1:
The heat pump system is divided into multiple stages (first stage, second stage, etc.), where each stage contains a heat pump unit with caloric material. This segmentation allows the system to achieve a cumulative temperature lift by cascading multiple smaller temperature differences, resolving the contradiction between limited material temperature swing and required application temperature range.
2Temperature
If coolant flow is split between hot side and cold side in each stage, then the temperature range is improved, but the usable coolant flow is reduced
Solution Approach 1:
The patent implements continuous circulation of coolant through a closed loop system with return lines. Coolant that has been heated in one stage is continuously returned to previous stages to be cooled, maintaining continuous useful action. This resolves the contradiction by ensuring that coolant flow is continuously reused rather than being consumed or lost in the splitting process.
Solution Approach 2:
The system recovers coolant from later stages and returns it to earlier stages through return lines. Instead of discarding the coolant after a single pass, the system recovers and reuses it in subsequent cycles, maintaining adequate coolant flow while achieving extended temperature ranges through multiple stages.
3Quantity of substance
If multiple stages with return lines are implemented, then the usable coolant flow is increased, but the device complexity increases
Solution Approach 1:
The return lines serve multiple functions: they transport coolant between stages, enable heat recovery, and maintain system pressure. This multi-functionality reduces the need for additional dedicated components, thereby increasing usable coolant flow while limiting the growth of device complexity.
Solution Approach 2:
The patent merges the coolant transport function with the heat exchange function by using the same lines for both purposes. The return lines simultaneously serve as coolant conduits and heat transfer pathways, combining multiple functions into unified components to reduce overall system complexity while enhancing coolant flow utilization.
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 allows for a significant increase in the usable coolant flow and temperature range, improving the efficiency of the heat pump cascade by recycling coolant flows, thereby addressing the limitations of existing caloric heat pumps.
Implementation Method 1
This temperature difference is limited by the temperature change of the calorific material during phase transition
Implementation Method 2
each heat pump has a volume flow divider, wherein the volume flow divider is configured to divide a coolant flow entering the coolant inlet between the hot side and the cold side
Implementation Method 3
the second coolant outlet of the heat pump of at least one subsequent stage i+1 with i=1 ... n-1 is connected by means of a return line to the coolant inlet of the heat pump of a preceding stage 1 ... i
Data Source
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AI summary
To provide a heat pump cascade capable of delivering a high temperature lift with high efficiency, a heat pump cascade (100) comprising n stages with n ≥ 2 is proposed, wherein each of the n stages has a heat pump (10) with a coolant inlet (11), a first coolant outlet (12), and a second coolant outlet (13), wherein each heat pump (10) has a hot side (14) and a cold side (15) and a flow divider (24), the flow divider (24) being configured to split a coolant flow entering the coolant inlet (11) to the hot side (14) and the cold side (15), wherein the first coolant outlet (12) of the heat pump (10) of each stage i with i = 1...n-1 is connected to the coolant inlet (11) of the heat pump (10) of a subsequent stage i+1, and furthermore, the second coolant outlet (13) of the heat pump (10) at least one subsequent stage i+1 with i = 1...n-1 is connected to the coolant inlet (11) of the heat pump (10) of a preceding stage 1...i by means of a return line (21).