Air conditioning system comprising a system to control freezing of a heat exchanger of an air conditioning loop
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Solution Overview
Problem
Current air conditioning systems for vehicles face challenges in accurately and reliably controlling the icing of refrigerant fluid/ambient air heat exchangers, particularly in two-pass configurations, which affects thermal performance.
Innovation Solution
The system employs strategically placed temperature sensors to measure ambient and refrigerant fluid temperatures, using specific algorithms to determine icing conditions, including calculating heating power, saturation temperatures, and comparing estimated and actual compressor powers to detect frost on the external surface of the heat exchanger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are placed to measure ambient air and refrigerant fluid temperatures for determining icing conditions, then the ability to detect frost on the heat exchanger is improved, but the reliability and precision of icing state information remains insufficient for two-pass heat exchangers
Solution Approach 1:
The heat exchanger is divided into multiple zones (first zone and second zone) with separate temperature sensors for each zone. This segmentation allows independent monitoring of different regions, enabling more precise detection of localized icing conditions that affect the overall heat exchanger performance.
Solution Approach 2:
The control unit acts as an intermediary that receives temperature data from multiple sensors, processes the information through algorithms, and determines the overall icing state. This intermediary processing layer enhances reliability by cross-validating measurements and accounting for the two-pass configuration specifics.
2Productivity
If a two-pass refrigerant fluid/ambient air heat exchanger is used, then thermal performance is improved, but the complexity of accurately detecting icing conditions increases
Solution Approach 1:
The two-pass heat exchanger is segmented into distinct monitoring zones corresponding to each pass, with temperature sensors strategically placed in the first and second zones. This segmentation simplifies the detection complexity by breaking down the complex two-pass structure into manageable monitoring regions.
Solution Approach 2:
The temperature sensors and control unit serve multiple functions: they monitor both zones independently, detect icing conditions, and provide information for defrosting control. This multi-functionality reduces overall system complexity despite the two-pass configuration.
3Productivity
If frost forms on the external surface of the heat exchanger, then heat exchange between refrigerant fluid and ambient air is reduced, but the system lacks reliable information to detect and respond to icing conditions
Solution Approach 1:
The system implements feedback by continuously monitoring temperatures in both zones, processing the data through the control unit, and using the determined icing state information to trigger appropriate responses. This feedback loop ensures the system has reliable information to detect and respond to icing conditions that would otherwise go undetected.
Solution Approach 2:
The patent replaces direct physical measurement of frost with indirect thermal measurement using temperature sensors and algorithmic processing. This substitution provides reliable icing state information without requiring direct contact with the frost layer, maintaining heat exchange efficiency while enabling detection.
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 provides precise and reliable information on icing conditions, optimizing the operation of the air conditioning system and enhancing thermal performance by preventing frost-related heat exchange reductions.
Implementation Method 1
a first temperature sensor (20) arranged downstream of said coolant fluid/ambient air heat exchanger (10) in a direction of flow (100) of a flow of ambient air (11) through said coolant fluid/ambient air heat exchanger (10)
Implementation Method 2
a refrigerant fluid/ambient air heat exchanger for allowing heat exchange between the refrigerant fluid and an ambient air flow
Implementation Method 3
the coolant fluid picks up heat from the ambient air flow
Implementation Method 4
a compressor for compressing the refrigerant fluid
Implementation Method 5
at least one expansion device to allow expansion of the refrigerant fluid
Implementation Method 6
an external surface of the refrigerant/ambient air heat exchanger to become covered with frost
Data Source
Figure 1
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AI summary
The system has a control device for controlling freezing of an ambient air/cooling fluid heat exchanger (10) comprising two passes (P1, P2), and a temperature sensor (20) arranged in a zone situated opposite to one of the passes. The temperature sensor is placed at distances (X1, X2) from a separation line (27), where the distances are less than 66 percent of respective widths (L1, L2) of the passes. The temperature sensor is arranged downstream of the heat exchanger along a flow direction of an ambient air flow (11) through the heat exchanger. An independent claim is also included for a method for determining freezing state of an external surface of an ambient air/cooling fluid heat exchanger constituting an air conditioning system.