Vehicle A/C Control Using Heater Core Cooling During Engine Stop
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Solution Overview
Problem
In vehicles with start/stop systems, the automatic shutdown of the engine disrupts air conditioning, causing the evaporator temperature to rise and passenger cabin air to become warmer, as the refrigerant circuit is temporarily out of operation, leading to comfort issues and increased energy consumption.
Innovation Solution
A method for controlling the air conditioning system that transfers heat from the heat exchanger to air when the refrigerant circuit is not in operation and the evaporator temperature is higher, using the heating circuit to cool the air, ensuring efficient operation by utilizing existing components without additional structural parts or weight, and allowing for simple retrofitting of existing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is automatically switched off to save fuel during idle periods, then fuel consumption is reduced, but the evaporator temperature rises and air conditioning performance deteriorates
Solution Approach 1:
The system pre-cools the heat exchanger of the heating circuit before the engine shutdown using the refrigerant circuit. This preliminary cooling action ensures that when the engine is switched off, the heat exchanger can immediately provide cooling capacity to the evaporator, maintaining air conditioning performance during the idle period without requiring additional energy input.
Solution Approach 2:
The heating circuit's heat exchanger acts as an intermediary thermal storage device between the refrigerant circuit and the evaporator. It absorbs and stores cooling energy when the refrigerant circuit is active, then releases this stored energy to the evaporator when the engine is shut down, thereby mediating the temperature maintenance function during periods when the primary cooling system is inactive.
2Temperature
If additional cooling equipment is added to maintain cooling during engine shutdown, then air conditioning performance is maintained, but device complexity and weight increase
Solution Approach 1:
The heating circuit's heat exchanger, originally designed for heating functions, is made multi-functional by enabling it to store and release cooling energy. This allows the same component to serve both heating and cooling purposes depending on operational conditions, eliminating the need for separate dedicated cooling storage equipment and thereby reducing overall system complexity.
Solution Approach 2:
The heating circuit's heat exchanger serves itself as a thermal storage device for the cooling system. By utilizing its own thermal mass and heat transfer capability, it provides cooling capacity during engine shutdown without requiring external active cooling components, thereby maintaining air conditioning performance while avoiding additional device complexity.
3Temperature
If the heat exchanger is continuously cooled to maintain cooling capacity, then air conditioning performance is maintained, but energy consumption increases
Solution Approach 1:
Instead of continuous cooling, the system employs periodic cooling action only when the engine is about to be shut down or is in idle operation. The heat exchanger is cooled during these specific periods to store thermal energy, and then this stored energy is utilized during the shutdown period. This periodic approach maintains adequate cooling capacity while significantly reducing overall energy consumption compared to continuous operation.
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 reduces the additional load on the air conditioning system by using the heating circuit for cooling only when necessary, maintaining energy efficiency and passenger comfort without requiring additional equipment, and can be easily integrated into existing systems.
Implementation Method 1
transferring heat from the coolant circuit to air passing through the heat exchanger
Implementation Method 2
an evaporator operated as a cold exchanger of the air conditioning system
Data Source
AI summary
An air conditioning method is provided. The method comprises when a refrigerant circuit is in operation and a temperature of an evaporator of the refrigerant circuit is lower than a temperature of a heat exchanger of a heating circuit, transferring heat from the heat exchanger to air passing through the heat exchanger, and when the refrigerant circuit is not in operation and the temperature of the evaporator is higher than the temperature of the heat exchanger, transferring heat from the air passing through the heat exchanger to the heat exchanger. In this way, the heat exchanger functions to augment the cooling capabilities of the evaporator.