Vehicle HVAC system
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Solution Overview
Problem
In electric vehicles, the HVAC system's refrigerant fails to efficiently absorb heat from the power electronics coolant at low ambient temperatures, leading to reduced compressor efficiency and electric efficiency due to insufficient evaporation and condensation, resulting in reduced heating and dehumidification performance.
Innovation Solution
A vehicle HVAC system with a refrigerant circulation path including a compressor, interior condenser, water-cooled heat exchanger, exterior heat exchanger, refrigerant heat exchanger, and control valves to manage refrigerant flow, allowing for multiple bypass lines and valves to optimize heat transfer and evaporation in various modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the refrigerant absorbs heat from power electronics coolant through a water-cooled heat exchanger, then heating performance is improved, but at low ambient temperatures the refrigerant fails to sufficiently absorb heat leading to reduced compressor efficiency
Solution Approach 1:
A refrigerant heat exchanger is introduced as an intermediary component to transfer heat from the high-temperature refrigerant discharged from the interior condenser back to the refrigerant entering the water-cooled heat exchanger. This creates a heat recovery loop that ensures sufficient refrigerant evaporation even when ambient temperatures are low, maintaining compressor suction pressure and efficiency while improving overall heating performance.
2Use of energy by moving object
If the blower rate is reduced when target temperature is reached, then energy consumption is reduced, but the interior condenser fails to sufficiently release heat leading to insufficient refrigerant condensation
Solution Approach 1:
The refrigerant heat exchanger acts as a mediator to transfer heat from the hot refrigerant discharged from the interior condenser to the refrigerant entering the water-cooled heat exchanger. This heat recovery mechanism ensures that refrigerant condensation is maintained even when the blower rate is reduced, allowing energy-efficient operation without compromising dehumidification performance.
3Temperature
If the electric heater is used to heat the passenger compartment due to refrigerant heating failures, then heating is maintained, but electric efficiency of the vehicle is reduced
Solution Approach 1:
The refrigerant heat exchanger recovers heat from the high-temperature refrigerant discharged from the interior condenser and transfers it to the refrigerant entering the water-cooled heat exchanger. This heat recovery mechanism ensures sufficient refrigerant evaporation at low ambient temperatures, maintaining compressor operation and refrigerant-based heating performance, thereby avoiding the need to use the electric heater and preserving vehicle electric efficiency.
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 and dehumidification performance by ensuring sufficient refrigerant evaporation and condensation, maintaining compressor efficiency, and minimizing electric heater usage, thereby improving the electric vehicle's overall efficiency.
Implementation Method 1
a water-cooled heat exchanger positioned on a downstream side of the interior condenser, the water-cooled heat exchanger being configured to transfer heat between a refrigerant and a coolant circulating in a coolant system
Implementation Method 2
an exterior heat exchanger positioned on a downstream side of the water-cooled heat exchanger, the exterior heat exchanger being configured to transfer heat between the refrigerant and ambient air
Implementation Method 3
a refrigerant heat exchanger configured to transfer heat between the refrigerant discharged from the water-cooled heat exchanger and the refrigerant discharged from the interior condenser
Implementation Method 4
a compressor
Implementation Method 5
an interior condenser positioned on a downstream side of the compressor
Data Source
AI summary
A vehicle HVAC system includes a compressor, an interior condenser disposed on the downstream side of the compressor, a water-cooled heat exchanger disposed on the downstream side of the interior condenser, and configured to transfer heat between a refrigerant and a coolant circulating in a coolant system, an exterior heat exchanger disposed on the downstream side of the water-cooled heat exchanger, and configured to transfer heat between the refrigerant and ambient air; a refrigerant heat exchanger configured to transfer heat between the refrigerant discharged from the water-cooled heat exchanger and the refrigerant discharged from the interior condenser, and a first control valve located between the water-cooled heat exchanger and the interior condenser, and configured to allow the refrigerant discharged from the interior condenser to be directed to at least one of the water-cooled heat exchanger, the refrigerant heat exchanger, and the exterior heat exchanger.