Vehicle Heat Pump Refrigerant Bypass for Defrost and Dehumidification
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Solution Overview
Problem
Conventional heat pump systems for vehicles face inefficiencies in heating performance due to refrigerant temperature being lower than outdoor air, leading to frosting on exterior heat exchangers and reduced heat exchange efficiency, and are unable to effectively dehumidify the interior in heat pump mode.
Innovation Solution
A heat pump system with a dehumidification line that supplies refrigerant to the evaporator before the exterior heat exchanger, allowing for smooth flow at low pressure, and includes an auxiliary bypass line to bypass the exterior heat exchanger when frosting occurs, along with a controller to manage frosting prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If refrigerant flows through the exterior heat exchanger before the evaporator in heat pump mode, then heating performance is improved, but frosting occurs on the exterior heat exchanger when refrigerant temperature is lower than outdoor air temperature
Solution Approach 1:
The patent extracts the dehumidification function from the main heating cycle by creating a separate dehumidification line that branches off before the exterior heat exchanger and reconnects after the evaporator. This allows the evaporator to receive refrigerant independently of the exterior heat exchanger, enabling dehumidification without causing frosting on the exterior heat exchanger.
Solution Approach 2:
The refrigerant circulation path is segmented into multiple independent lines: a main heating line through the exterior heat exchanger and a separate dehumidification line through the evaporator. This segmentation allows independent control of each function, enabling the system to perform dehumidification while maintaining heating performance without frosting issues.
2Adaptability or versatility
If a dehumidification line is added to supply refrigerant to the evaporator before the exterior heat exchanger, then dehumidification capability is improved, but refrigerant flow becomes complex with pressure differential issues
Solution Approach 1:
The patent introduces a four-way valve as an intermediary device to manage the complex refrigerant flow paths. This valve acts as a mediator that directs refrigerant flow between different components (exterior heat exchanger, evaporator, compressor) based on operational mode, simplifying the control of the multi-path system without requiring complex piping modifications.
3Adaptability or versatility
If the evaporator pressure is lower than the exterior heat exchanger pressure, then refrigerant can flow to the evaporator for dehumidification, but reverse flow occurs when the dehumidification line connects after the exterior heat exchanger
Solution Approach 1:
The patent implements preliminary action by positioning the dehumidification line connection points strategically: before the exterior heat exchanger on the high-pressure side and after the evaporator on the low-pressure side. This preliminary arrangement of the flow path ensures that refrigerant naturally flows from high to low pressure through the evaporator for dehumidification, preventing reverse flow issues.
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
Enhances heating performance by preventing frosting and ensuring efficient dehumidification of the vehicle interior, even in low outdoor temperatures, by managing refrigerant flow and pressure effectively.
Implementation Method 1
a compressor (100) mounted on a refrigerant circulation line for compressing and discharging refrigerant
Implementation Method 2
an interior heat exchanger (110) mounted inside an air-conditioning case for exchanging heat between the air inside the air-conditioning case and the refrigerant discharged from the compressor
Implementation Method 3
an evaporator (160) mounted inside an air-conditioning case for exchanging heat between the air inside the air-conditioning case and the refrigerant supplied to the compressor
Implementation Method 4
an exterior heat exchanger (130) mounted outside the air-conditioning case for exchanging heat between the refrigerant circulating through the refrigerant circulation line and the outdoor air
Implementation Method 5
first expansion means (120) mounted on the refrigerant circulation line between the interior heat exchanger and the exterior heat exchanger for expanding refrigerant
Implementation Method 6
second expansion means (140) mounted on the refrigerant circulation line of an inlet side of the evaporator for expanding refrigerant
Data Source
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AI summary
A heat pump system for a vehicle, which includes a dehumidification line R4 for supplying some of refrigerant circulating a refrigerant circulation line R to an evaporator 160 before the refrigerant is introduced into an exterior heat exchanger 130 after passing a first expansion means 120 so as to dehumidify the interior of the vehicle in a heat pump mode, thereby allowing the refrigerant to smoothly flow to the evaporator 160 of a low pressure through the dehumidification line before the refrigerant is introduced into the exterior heat exchanger 130 which has a higher pressure than the evaporator when the interior of the vehicle is dehumidified, and smoothly dehumidifying the inside of the vehicle.