Vehicle Cabin Heating via Evaporator Bypass Refrigerant Control
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Solution Overview
Problem
Existing vehicle air conditioning systems take several to tens of minutes to heat the cabin due to the higher thermal inertia of engine coolant, leading to decreased fuel efficiency and increased fuel consumption from remote starts, and the method of using the compressor to generate heat reduces the A/C system's capacity to produce additional heat.
Innovation Solution
A controller manages the air conditioning system by routing refrigerant around the evaporator during startup to retain heat, then through the evaporator once a threshold temperature is reached, maximizing compressor efficacy and reducing heating time by adjusting blower speed and using an electric heater and refrigerant/coolant heat exchanger to maintain refrigerant temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat is taken out of the A/C system to heat the vehicle cabin, then the vehicle cabin heating is achieved, but the capacity of the A/C system to generate additional heat is reduced
Solution Approach 1:
The system performs preliminary heating by routing refrigerant through the evaporator before it would normally bypass, allowing the evaporator to function as a heater. This preliminary action generates heat in advance by utilizing the temperature difference between the refrigerant and ambient air, thereby achieving cabin heating without compromising the A/C system's subsequent heat generation capacity.
Solution Approach 2:
The invention inverts the normal function of the evaporator by routing hot refrigerant through it to heat the cabin, rather than using it to cool the cabin as in conventional A/C operation. This inversion allows the evaporator to serve as a heat source, utilizing the thermal energy in the refrigerant that would otherwise be wasted, thereby achieving cabin heating while preserving the system's ability to generate cooling when needed.
2Temperature
If the refrigerant temperature at the compressor inlet is reduced, then heat transfer at the evaporator is increased, but the compressor's ability to add heat/energy to the fluid is reduced
Solution Approach 1:
The system performs preliminary heating by routing refrigerant through the evaporator before it would normally bypass, allowing the evaporator to function as a heater. This preliminary action generates heat in advance by utilizing the temperature difference between the refrigerant and ambient air, thereby achieving cabin heating without compromising the A/C system's subsequent heat generation capacity.
Solution Approach 2:
The invention maintains continuous useful action by ensuring the refrigerant retains sufficient temperature and pressure to continue adding heat in the compressor. By carefully controlling the refrigerant flow and temperature through the evaporator, the system ensures that the refrigerant remains capable of effective compression and heat addition, thereby maintaining continuous heat generation capability throughout the A/C cycle.
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 minimizes the time to provide instant cabin heat, reduces the need for remote starts, and increases fuel efficiency by maximizing the A/C system's heat generation and maintaining refrigerant temperature above the threshold.
Implementation Method 1
The pressurized refrigerant vapors from the compressor then enter a condenser, where they are converted into a liquid, releasing heat.
Implementation Method 2
a cooling air is typically generated by flowing air around an evaporator that is cooled when a refrigerant expands in the evaporator, thereby absorbing heat from the surrounding air
Implementation Method 3
The pressurized refrigerant vapors from the compressor then enter a condenser, where they are converted into a liquid, releasing heat.
Implementation Method 4
Air is flowed across the evaporator by a blower, heating the air before routing it into the vehicle cabin.
Data Source
AI summary
Methods and system for providing heat to a vehicle are presented, whereby a refrigerant loop is operated to heat a cabin of the vehicle via heat generated by a compressor and heat generated by a resistive heating element. The heat generated by the compressor and the heat generated by the resistive heating element are transferred to a refrigerant before it is transferred to the cabin. In one example, in a first mode, an evaporator bypass valve on an evaporator bypass conduit of the A/C system is opened to route the refrigerant around an evaporator of the A/C system to increase a temperature of the refrigerant in the refrigerant loop; and in a second mode, the evaporator bypass valve is closed to route the refrigerant through the evaporator, where heat is released to a flow of air across the evaporator that is directed to the vehicle cabin.