Cold-Storage HVAC Loop for Cooling During Engine Stops
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Solution Overview
Problem
Current heating, ventilation, and air conditioning (HVAC) systems in vehicles with stop-start engines face challenges in maintaining comfort during engine shutdowns, as existing solutions like storage evaporators have limited autonomy, increased pressure drop, and complexity, and double-loop systems are cumbersome.
Innovation Solution
A simplified HVAC system with a main thermodynamic loop and a secondary air conditioning loop that includes a cold storage heat exchanger and a 'three-way' valve for fluid circulation, allowing for efficient cold storage and retrieval when the compressor is off, using a single fluid circulation branch and a refrigerant pressure reducer for improved storage times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If storage evaporators with phase change material are used to maintain cooling during engine stop, then air conditioning continuity is improved, but system complexity and pressure drop increase
Solution Approach 1:
The system is divided into a main thermodynamic loop for active cooling and a secondary loop with cold storage for passive cooling during engine stops. This segmentation allows each loop to be optimized independently, reducing overall system complexity while maintaining air conditioning continuity.
Solution Approach 2:
Cold is stored in the cold storage heat exchanger during engine operation before the engine stops. This preliminary action of storing cold energy allows the secondary loop to maintain cooling without requiring complex real-time control during engine stop, simplifying the overall system.
2Duration of action of stationary object
If storage evaporators with phase change material are used to maintain cooling during engine stop, then air conditioning continuity is improved, but pressure drop increases requiring more powerful fan motors
Solution Approach 1:
The fluid circulation path is segmented into main and secondary loops. The secondary loop uses a separate fluid circulation path with the cold storage heat exchanger, avoiding the pressure drop issues in the main evaporator path while maintaining cooling effectiveness.
3Device complexity
If conventional evaporators are used, then system simplicity is maintained, but cooling function stops when engine stops
Solution Approach 1:
The invention merges a conventional evaporator with a cold storage heat exchanger into an integrated system. The cold storage component is added to the conventional evaporator setup, combining the simplicity of the original system with the extended cooling duration provided by the cold storage during engine stops.
Solution Approach 2:
The cold storage heat exchanger serves multiple functions: it acts as a heat exchanger during engine operation and as a cold storage device during engine stops. This multi-functionality allows the system to maintain simplicity while extending cooling continuity without requiring completely separate systems.
4Duration of action of stationary object
If double-loop systems with separate thermodynamic loops are used, then air conditioning continuity is improved, but system complexity and space requirements increase
Solution Approach 1:
The cold storage heat exchanger is nested within or integrated with the existing evaporator structure. This nesting approach allows the secondary cooling function to be accommodated within the space already allocated for the evaporator, minimizing additional space requirements while providing air conditioning continuity during engine stops.
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 maintains passenger compartment comfort by prolonging air conditioning functionality during engine stops, reducing system complexity, and optimizing energy use, while minimizing space and cost requirements.
Implementation Method 1
a heat exchanger with cold storage, able to store cold during operation of the compressor
Implementation Method 2
a thermodynamic secondary air conditioning loop integrating the heat exchanger with cold storage and intended to cool the evaporator when the compressor is not in operation
Implementation Method 3
the refrigerant fluid then passes through an evaporator in which it exchanges heat with the air intended for the heat treatment of the passenger compartment of the vehicle. To do this, the evaporation of the refrigerant at low temperature requires an energy input which is provided by the air passing through the evaporator.
Implementation Method 4
the refrigerant fluid then passes through an evaporator in which it exchanges heat with the air intended for the heat treatment of the passenger compartment of the vehicle
Implementation Method 5
The high-pressure gas-phase refrigerant then passes through a condenser and exchanges heat with ambient air coming directly from the front of the vehicle and/or from a fan. At the outlet of the condenser, the refrigerant fluid is in the high pressure liquid phase.
Implementation Method 6
The high-pressure gas-phase refrigerant then passes through a condenser and exchanges heat with ambient air
Implementation Method 7
an expansion device, in particular an expansion valve, makes it possible to reduce the pressure and the temperature of the refrigerant fluid in the liquid phase
Data Source
Figure 1a~1b
Figure 2a~2b
AI summary
The installation has a main thermodynamic air-conditioning loop (10) for circulating refrigerant i.e. R134a, and a heat exchanger (21) for cold storage during functioning of a compressor (11) of the main loop. A secondary thermodynamic air-conditioning loop (20a) integrates the exchanger and cools an evaporator (14) of the main loop when the compressor is not operation. The secondary loop has a single circulation branch placed in parallel on a common section with the main loop and formed by a circulation pump (25). The exchanger of the branch cools the refrigerant for the evaporator.