Vehicle HVAC Dual-Loop Thermal Management for Waste-Heat Heating
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Solution Overview
Problem
Conventional HVAC systems for vehicles, especially electric and hybrid vehicles, face inefficiencies in energy consumption and cost, particularly in heating the cabin, which affects the electric range and overall system performance.
Innovation Solution
A dual-loop HVAC system with a primary loop for coolant circulation and a secondary loop for refrigerant, utilizing multiple heat sources and heat exchangers, including waste heat from the vehicle's motor and an electric heater, to efficiently heat the cabin through various operational modes such as preconditioning, heating, dry heating, and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a conventional HVAC system uses a compressor and refrigerant loop to cool the cabin, then cooling function is achieved, but energy consumption increases significantly
Solution Approach 1:
The system divides the thermal management into separate loops: a primary coolant loop that can operate independently for cooling, and a secondary refrigerant loop that activates only when additional cooling capacity is needed. This segmentation allows the high-energy refrigerant system to remain idle during mild cooling conditions, reducing overall energy consumption while maintaining reliable cooling function.
Solution Approach 2:
The system changes the operating parameters by using coolant temperature and cabin temperature thresholds to determine when to switch between different cooling modes. When coolant temperature exceeds a first threshold, the primary cooling mode activates; when cabin temperature exceeds a second threshold, the refrigerant cooling mode activates, optimizing energy usage based on real-time thermal conditions.
2Ease of operation
If the HVAC system activates cooling functions early, then cabin comfort is improved, but electric range is reduced due to higher energy consumption
Solution Approach 1:
The system performs preliminary cooling actions by activating the coolant-based primary cooling system before the refrigerant-based secondary system. This preliminary action addresses immediate cooling needs with lower energy consumption, reserving the high-energy refrigerant system for more severe thermal conditions, thereby extending electric range while maintaining cabin comfort.
Solution Approach 2:
The system substitutes the mechanical refrigerant compression system with a simpler coolant circulation-based cooling system for preliminary cooling operations. This substitution reduces mechanical complexity and energy consumption during early cooling phases, preserving electric range while providing adequate cabin comfort.
3Use of energy by stationary object
If multiple heat sources and heat exchangers are added to improve heating efficiency, then heating performance is enhanced, but system complexity increases
Solution Approach 1:
The system implements multi-functionality by designing the coolant circulation system to serve dual purposes: primary cooling through radiator dissipation and primary heating through heat exchanger recovery. The same coolant loop can switch between cooling and heating modes based on thermal conditions, reducing the need for separate dedicated systems and thereby limiting complexity increase despite enhanced heating efficiency.
Solution Approach 2:
The system converts waste heat from the coolant into a useful heating resource. By capturing thermal energy that would otherwise be lost and redirecting it through heat exchangers to warm the cabin, the system improves heating efficiency while using existing infrastructure, thereby limiting the increase in system complexity.
4Power
If the refrigerant loop is always active, then cooling capacity is maximized, but energy consumption increases
Solution Approach 1:
The system applies dynamics by making the refrigerant loop operational status variable rather than fixed. The refrigerant compressor and associated components activate only when thermal conditions warrant additional cooling capacity, dynamically adjusting system operation to match actual cooling demands, thereby maximizing cooling capacity only when needed while minimizing energy consumption during milder conditions.
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 significantly improves heating efficiency by utilizing waste heat, reducing energy consumption, and extending the electric range of vehicles, particularly during the initial 20 minutes of operation when HVAC systems typically use the most energy.
Implementation Method 1
a first heat exchanger. The first sub-loop may partially extend into the case of the HVAC system to place the first heat exchanger adjacent an air heater
Implementation Method 2
a second heat exchanger. The secondary loop exchanging heat with the second sub-loop of the primary loop
Implementation Method 3
The secondary loop may include a third heat exchanger, a compressor, an expansion valve, and an evaporator
Implementation Method 4
The secondary loop may include a third heat exchanger, a compressor, an expansion valve, and an evaporator
Implementation Method 5
The secondary loop may include a third heat exchanger, a compressor, an expansion valve, and an evaporator
Implementation Method 6
The secondary loop may include a third heat exchanger, a compressor, an expansion valve, and an evaporator
Data Source
AI summary
The present disclosure provides an HVAC system for a vehicle having a first heat source and having a primary loop through which a coolant circulates and a secondary loop through which refrigerant circulates. The primary loop having two parallel sub-loops, namely a first sub-loop and a second sub-loop in which the coolant may circulate. The first sub-loop of the primary loop includes the first heat source, a second heat source, and a first heat exchanger. The first sub-loop may partially extend into a case of the HVAC system to place the first heat exchanger adjacent an air heater. The second sub-loop of the primary loop includes the first heat source, the second heat source, and a second heat exchanger. The HVAC system having a plurality of operation modes for efficiently conditioning air in a cabin of the vehicle.