Vehicle Exterior Heat Exchanger Defrost Priority for Heating Capacity
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Solution Overview
Problem
Existing vehicle air conditioning systems face challenges in maintaining heating capacity during defrosting operations due to frost formation on vehicle-exterior heat exchangers, particularly when multiple heat exchangers are used, as they do not effectively manage frost formation and air flow resistance.
Innovation Solution
A vehicle air conditioning system with a refrigerant circuit and a heat medium circuit, featuring multiple vehicle-exterior heat exchangers, includes a detection unit to assess frost formation and a control device to strategically switch the flow of a high-temperature or low-temperature medium to specific heat exchangers based on frost detection, prioritizing defrosting of the upwind heat exchanger to maintain air flow and heating capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple vehicle-exterior heat exchangers are used to enhance heating capacity, then heating capacity is improved, but frost formation on heat exchangers occurs more readily
Solution Approach 1:
The vehicle-exterior heat exchanger is divided into multiple segments (first heat exchanger and second heat exchanger) arranged in series. This segmentation allows independent defrosting control of each segment based on frost detection, enabling selective defrosting of only the affected segments rather than the entire heat exchanger system, thus resolving the contradiction between maintaining multiple heat exchangers for heating capacity and managing frost formation.
Solution Approach 2:
The detection unit continuously monitors frost formation on each heat exchanger segment before it significantly impacts performance. The control device initiates defrosting operations proactively based on detection results, preventing severe frost accumulation that would compromise heating capacity. This preliminary action approach maintains the benefits of multiple heat exchangers while preemptively addressing frost issues.
2Object-affected harmful factors
If defrosting operation is performed on vehicle-exterior heat exchangers, then frost is removed, but heating capacity is reduced during the defrosting process
Solution Approach 1:
By segmenting the heat exchanger into multiple independently controllable units and arranging them in series, the system enables selective defrosting of only the affected segment while the other segment continues to provide heating. This segmentation strategy maintains partial heating capacity during defrosting operations, resolving the contradiction between frost removal and heating capacity maintenance.
Solution Approach 2:
The system merges the functions of multiple heat exchangers arranged in series, where one heat exchanger performs defrosting while the other simultaneously provides heating. This functional merging allows the system to achieve both frost removal and heating capacity maintenance concurrently, rather than treating them as mutually exclusive operations.
3Productivity
If the detection unit monitors each heat exchanger individually, then defrosting efficiency is improved, but device complexity increases
Solution Approach 1:
The detection unit is segmented to monitor each heat exchanger independently, and the control device is configured to process detection results for selective defrosting control. This segmentation enables efficient defrosting by targeting only affected areas, and the control logic is designed to manage the segmented monitoring without proportionally increasing complexity, thus resolving the contradiction between defrosting efficiency and system complexity.
4Reliability
If the first heat exchanger on the upwind side is prioritized for defrosting, then air flow resistance is minimized, but control complexity increases
Solution Approach 1:
The control device is programmed with predetermined control logic that prioritizes defrosting of the upwind heat exchanger based on its position in the series arrangement. This preliminary programming of defrosting priority prevents air flow resistance issues before they occur, and the logic is designed to be straightforward (prioritize upwind position) rather than complex, thus resolving the contradiction between air flow maintenance and control complexity.
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 ensures that frost formation on the upwind heat exchanger is addressed first, maintaining air flow and heating capacity during defrosting, allowing for efficient heat exchange recovery and early completion of defrosting, thus ensuring continuous heating performance.
Implementation Method 1
a heat medium circuit including a high-temperature medium circuit in which a heat medium absorbing heat from the refrigerant in the refrigerant circuit circulates
Implementation Method 2
a low-temperature medium circuit in which a heat medium dissipating heat to the refrigerant in the refrigerant circuit circulates
Implementation Method 3
a vehicle-interior heat exchanger configured to exchange heat between the heat medium and air
Implementation Method 4
a vehicle-exterior heat exchanger configured to exchange heat between the heat medium and air
Implementation Method 5
a defrosting mode in which the heat medium in the high-temperature medium circuit is supplied to a defrosting target
Implementation Method 6
the heat medium in the high-temperature medium circuit is supplied to a defrosting target to be selected as either the first heat exchanger or the second heat exchanger
Data Source
AI summary
A vehicle air conditioning system includes a refrigerant circuit, a heat medium circuit, a vehicle-interior heat exchanger, a vehicle-exterior heat exchanger including a first heat exchanger and a second heat exchanger disposed in series with respect to a flow of air generated by an air blower, a switching unit, a detection unit for detecting a degree of frost formation, and a control device. The operation mode includes a defrosting mode in which the heat medium in the high-temperature medium circuit is supplied to a defrosting target to be selected as either the first or second heat exchanger by the operation of the switching unit. The control device selects, as the defrosting target, the first heat exchanger in preference to the second heat exchanger when determined that both the first and the second heat exchangers need to be defrosted.