Parallel Heat Exchangers for Vehicle HVAC Efficiency
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Solution Overview
Problem
Secondary loop vehicle heating and cooling systems face challenges with reduced energy efficiency and increased hardware costs due to indirect heat transfer and the need for additional components like chillers, coolant pumps, and reservoirs, while also requiring smaller, more expensive heat exchangers when operated in parallel.
Innovation Solution
A vehicle heating and cooling system with first and second air-to-coolant heat exchangers connected in parallel, controlled by a module that directs coolant flows through the heat exchangers based on operation mode, using four-way valves and pumps to optimize temperature control without the need for blend doors, and incorporating manifolds and reservoirs for efficient coolant management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If heat exchangers are operated in parallel to reduce size and cost, then device complexity and cost are reduced, but energy efficiency decreases due to indirect heat transfer
Solution Approach 1:
The system dynamically switches between parallel heat exchanger operation (for reduced size/cost) and series heat exchanger operation (for improved energy efficiency) based on real-time thermal load conditions. The control module monitors cabin temperature and thermal demand, selecting the optimal configuration: parallel mode when rapid cooling/heating is needed and series mode when energy conservation is prioritized, thus resolving the contradiction between device size reduction and energy efficiency maintenance.
Solution Approach 2:
The system changes the operational parameters of the heat exchangers by switching their connection configuration (parallel vs. series) and adjusting coolant flow rates through electronic control of pumps and valves. This parameter change allows the system to optimize the trade-off between heat exchanger size and energy efficiency, using parallel configuration for compactness and series configuration for thermal efficiency depending on operating conditions.
2Reliability
If a secondary loop system is used to isolate the refrigerant circuit, then safety is improved for using low-GWP refrigerants, but device complexity increases due to added hardware
Solution Approach 1:
The system merges the climate control loop and battery thermal management loop into a single integrated secondary loop system. Both systems share common components including the coolant pump, reservoir, and heat exchangers, eliminating the need for separate hardware systems. This consolidation maintains safety by isolating the refrigerant circuit while using low-GWP refrigerants, but reduces overall device complexity through component sharing and system integration.
Solution Approach 2:
The secondary loop system components serve multiple functions: the coolant pump and heat exchangers are used for both climate control and battery thermal management. This multi-functionality reduces the total number of hardware components needed while maintaining the safety benefits of refrigerant circuit isolation, effectively resolving the contradiction between safety and device complexity.
3Device complexity
If coolant flow rates are adjusted through each heat exchanger for temperature control, then blend doors are eliminated, but device complexity increases due to control requirements
Solution Approach 1:
The system replaces the mechanical blend door system with an electronic control system that regulates coolant flow rates through the heat exchangers. Instead of using mechanical components to mix hot and cold air, the system uses electronically controlled pumps and valves to precisely control the temperature of coolant entering each heat exchanger, thereby eliminating mechanical blend doors while managing control complexity through electronic automation.
Solution Approach 2:
The system uses hydraulic control (coolant flow rate regulation) to achieve temperature control instead of mechanical blend doors. By precisely controlling the flow rate of coolant through each heat exchanger using electronic pumps and valves, the system achieves thermal regulation without mechanical moving parts, replacing the mechanical system with a fluid-based control mechanism.
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 reduces the size and cost of heat exchangers, enhances energy efficiency, and allows for effective temperature control in various modes of operation, including cooling, heating, and dehumidification, while eliminating the need for blend doors and minimizing coolant leakage.
Implementation Method 1
first and second air-to-coolant heat exchangers connected in parallel... allow the first flow of coolant to be directed through at least one of the first and second air-to-coolant heat exchangers
Implementation Method 2
air-to-coolant heat exchangers... provide cooling or heating
Data Source
AI summary
A vehicle having a heating and cooling system includes a cold source through which a first flow of coolant flows, a heat source through which a second flow of coolant flows, and first and second parallel connected air-to-coolant heat exchangers. The first and second coolant flows are directed through one or both of the air-to-coolant heat exchangers dependent upon a mode of operation. A control module controls the first and second flows of coolant dependent upon the mode of operation.