Outdoor Heat Exchanger Frost Prevention with Auxiliary Heating

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Solution Overview

Problem

In heating modes of vehicular air-conditioning systems, frost formation on outdoor heat exchangers reduces heat exchange performance, leading to inadequate heating capabilities in vehicles, especially in hybrid and electric cars.

Innovation Solution

The system calculates a requested refrigerant evaporation temperature to prevent frost formation by coordinating the heating of the radiator and auxiliary heating means, using a frost point and outdoor air temperature to ensure efficient heat transfer without causing frost on the outdoor heat exchanger.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the refrigerant evaporation temperature is lowered to increase heating capability, then the heating performance is improved, but frost formation occurs on the outdoor heat exchanger

Engineering Contradiction:

Improveheating capabilityVSAvoidfrost formation

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent introduces auxiliary heating means as an intermediary device that heats the air supplied to the vehicle interior. This allows the outdoor heat exchanger to operate at lower temperatures for efficient heat pumping while the auxiliary heater compensates for any temperature deficiency, preventing frost formation without sacrificing heating capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The control means dynamically adjusts the refrigerant evaporation temperature based on outdoor air temperature and required heating capability. By optimizing this parameter in real-time, the system maintains maximum heating efficiency while keeping the evaporation temperature above the frost point, thus preventing frost formation

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the outdoor heat exchanger operates at low temperature to absorb heat from outdoor air, then heat exchange efficiency is improved, but frost formation reduces heat exchange performance

Engineering Contradiction:

Improveheat exchange efficiencyVSAvoidheat exchange performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The control means continuously monitors outdoor air temperature and adjusts the refrigerant evaporation temperature accordingly. This feedback mechanism ensures the evaporation temperature remains optimized for heat exchange efficiency while staying above the frost point, preventing frost formation that would degrade heat exchange performance

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary heating of the supplied air using auxiliary heating means before it reaches the vehicle interior. This allows the outdoor heat exchanger to operate at optimal low temperatures for heat absorption without risk of frost formation, as the auxiliary heater will compensate for any temperature shortfall

Inventive Principle:

Principle #10Preliminary action

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 allows for effective heating of the vehicle interior while preventing frost formation on the outdoor heat exchanger, maintaining performance and reducing energy consumption, thereby enhancing the vehicle's heating capability and extending its cruising range.

Implementation Method 1

a radiator which lets the refrigerant radiate heat to heat the air to be supplied from the air flow passage into the vehicle interior

Methodology Applied

Scientific EffectHeat radiation: Thermal Radiation

Implementation Method 2

a heat absorber which lets the refrigerant absorb heat to cool the air to be supplied from the air flow passage into the vehicle interior

Methodology Applied

Scientific EffectHeat absorption: Absorption (physical)

Implementation Method 3

the refrigerant by which heat has been radiated is decompressed and then absorbs heat in the outdoor heat exchanger

Methodology Applied

Scientific EffectHeat absorption: Absorption (physical)

Implementation Method 4

a compressor which compresses a refrigerant

Methodology Applied

Scientific EffectCompression heating: Adiabatic Heating

Data Source

PatentUS9797641B2Vehicular air-conditioning device

Publication Date: 2017.10.24 SANDEN CORP

AI summary

There is disclosed an air-conditioning device of a so-called heat pump system which acquires comfortable heating in a vehicle interior by preventing or inhibiting frost formation to an outdoor heat exchanger. In a vehicular air-conditioning device 1, a controller calculates a requested refrigerant evaporation temperature in non-frosting TXObaseQtgt which is a refrigerant evaporation temperature of an outdoor heat exchanger 7 when a required heating capability Qtgt as a heating capability required for a radiator 4 is realized in non-frosting of the outdoor heat exchanger 7, and the controller controls heating by the radiator 4 and heating by a heating medium-air heat exchanger 40 of a heating medium circulating circuit 23 on the basis of the requested refrigerant evaporation temperature in non-frosting TXObaseQtgt and a frost point Tfrost to achieve the required heating capability Qtgt without causing frost formation to the outdoor heat exchanger 7.