Engine Coolant Heat Pump Coupling for Cold-Weather Cabin Heating
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Solution Overview
Problem
In hybrid and electric vehicles with range extenders, low ambient temperatures limit the availability of waste heat for heating the passenger compartment, reducing energy efficiency and electric range, as the combustion engine is shut off during electric-only driving phases.
Innovation Solution
Thermal coupling of a fluid circuit and a heat pump circuit allows heat transfer between them, utilizing the combustion engine as a heat source for the heat pump, especially at low temperatures, to enhance thermal conditioning of the engine and passenger compartment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the combustion engine is shut off during electric-only driving phases, then the electric range is extended, but the availability of waste heat for heating the passenger compartment is insufficient at low ambient temperatures
Solution Approach 1:
A heat pump circuit is introduced as an intermediary device between the combustion engine and the passenger compartment heating system. The heat pump includes a vaporizer that receives coolant from the combustion engine cooling circuit, a compressor, a condenser, and an expansion element. This intermediary system enables efficient heat transfer from the engine coolant to the passenger compartment air, especially when the engine is shut off, by using the heat pump's compression cycle to transfer heat from the vaporizer (connected to engine coolant) through the condenser to the passenger compartment.
Solution Approach 2:
The system changes the thermal parameters by using the heat pump circuit to actively manage heat transfer. The heat pump compressor increases the temperature and pressure of the refrigerant, enabling heat to be transferred from the cooler engine coolant (in the vaporizer) to the warmer passenger compartment environment (via the condenser). This parameter transformation allows heating capability to be maintained even when the combustion engine is shut off and not producing waste heat.
2Temperature
If an electric heating device is provided for additional heating, then the passenger compartment can be heated at low temperatures, but the electric range is significantly reduced
Solution Approach 1:
The heat pump system uses the combustion engine's own cooling circuit as a heat source. The vaporizer of the heat pump is integrated with the engine cooling circuit, allowing the system to extract heat from the engine coolant itself. This self-service approach eliminates the need for separate electric heating elements, as the engine's thermal management system doubles as a heat source for the heat pump, thereby maintaining heating capability without significant additional electric power consumption.
Solution Approach 2:
The combustion engine cooling circuit serves multiple functions: it cools the combustion engine during operation and simultaneously serves as a heat source for the heat pump circuit when heating is required. This multi-functionality allows the same coolant system to perform both cooling and heating roles, eliminating the need for separate heating systems and reducing overall energy consumption.
3Use of energy by moving object
If heat pumps are used to produce greater heat output, then the energy efficiency is improved compared to electric heaters, but the system complexity increases
Solution Approach 1:
The heat pump circuit is merged with the existing combustion engine cooling circuit. The vaporizer of the heat pump is integrated into the engine cooling system, allowing the refrigerant to exchange heat with the engine coolant. This merging eliminates the need for separate heating infrastructure and leverages the existing cooling system components, thereby reducing overall system complexity while maintaining high energy efficiency through the heat pump's coefficient of performance.
4Use of energy by moving object
If the combustion engine is used as a heat store to reduce heat output requirement, then the electric power input is reduced, but the thermal conditioning control becomes more complex
Solution Approach 1:
The system incorporates feedback control through the heat pump circuit that continuously monitors and adjusts heat transfer based on thermal conditions. The heat pump compressor and expansion element regulate refrigerant flow to maintain optimal heat exchange between the engine coolant (vaporizer) and the passenger compartment (condenser). This feedback mechanism automatically balances thermal loads, reducing the need for additional electric heating power while maintaining simple control through integrated thermal management.
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 approach improves energy efficiency by utilizing the combustion engine as a heat source, reducing the energy required for electric heating and extending the vehicle's electric range by providing efficient heating during cold conditions.
Implementation Method 1
transferring heat at least in some operational states of the vehicle from the fluid circuit or a sub-circuit of the fluid circuit to the heat pump circuit
Implementation Method 2
heat produced by the heat pump circuit is transferred via a heat exchanger to a (second) sub-circuit and from the second sub-circuit via a heating heat exchanger to the air flowing into the passenger compartment
Implementation Method 3
preheat the combustion engine through discharge of heat produced by the heat pump circuit to the fluid circuit via a heat exchanger
Data Source
AI summary
Thermal conditioning of a combustion engine of a vehicle is achieved by means of a fluid circuit or a sub-circuit of the fluid circuit and/or the air flowing into a passenger compartment of the vehicle by means of a heat pump circuit. In at least one operational state of the vehicle, heat is transferred from the fluid circuit or the sub-circuit of the fluid circuit to the heat pump circuit.