Vehicle HVAC Airflow Bypass for Stratified Cabin Heating
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Solution Overview
Problem
Conventional HVAC systems for vehicles face challenges in maintaining temperature stratification and energy efficiency, particularly in electric or partial-electric vehicles, where limited waste heat and high energy storage capacity lead to reduced comfort and increased energy losses.
Innovation Solution
The method involves an HVAC system with a main flow passage and bypass, utilizing a stratification door and heat exchanger to deliver only the necessary energy for comfort, minimizing energy losses by controlling the heating temperature and air flow to achieve stratified air distribution, independent of vehicle operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a coolant/air heat exchanger is used to heat air in the passenger compartment, then heating function is provided, but at low ambient temperatures the heat loss of efficient internal combustion engines is not sufficient to heat coolant to the required temperature level
Solution Approach 1:
The patent changes the operational parameters of the HVAC system by introducing a bypass channel that allows coolant to bypass the heating heat exchanger when engine temperatures are insufficient. This parameter change enables the system to adapt to low ambient temperature conditions while maintaining engine efficiency, as the coolant can be heated to required levels without excessive engine load or waste heat dissipation.
Solution Approach 2:
The patent segments the coolant flow path into two separate channels: a main flow passage through the heating heat exchanger and a bypass channel. This segmentation allows independent control of heat transfer processes, enabling the system to optimize coolant temperature for both engine performance and passenger compartment heating requirements.
2Temperature
If air mass flow is controlled by splitting into partial flows using a door, then temperature adjustment is achieved, but thermal stratification occurs at intermediate positions reducing passenger comfort
Solution Approach 1:
The patent applies local quality by providing different temperature characteristics at different outlet locations. The bypass channel delivers cooler air to specific regions while the main flow passage delivers heated air to other regions, creating localized temperature zones that improve overall passenger comfort rather than uniform temperature distribution.
Solution Approach 2:
The bypass channel acts as an intermediary flow path that mediates between the heating heat exchanger and the passenger compartment outlets. It allows cool air to mix with heated air at the outlet level, providing temperature modulation without requiring complex door mechanisms and eliminating thermal stratification issues.
3Use of energy by moving object
If coolant mass flow is controlled using a valve, then heat transfer is adjustable, but discontinuities in coolant flow due to varying engine speeds produce unintended effects and undesired thermal stratifications
Solution Approach 1:
The patent ensures continuous coolant flow through the bypass channel regardless of engine speed variations. The bypass provides a stable, uninterrupted flow path that maintains consistent thermal conditions in the passenger compartment, eliminating the discontinuities and thermal stratifications caused by valve-controlled intermittent flow.
4Temperature
If waste heat is dissipated to the environment in traditional engine-driven vehicles, then engine cooling is achieved, but in electric or partial-electric vehicles with limited waste heat this leads to increased energy losses
Solution Approach 1:
The HVAC system provides self-service by utilizing available waste heat from the engine or battery thermal management system through the heating heat exchanger. When waste heat is available, it automatically heats the bypass air, reducing or eliminating the need for additional heating energy in electric vehicles. The system adapts to available thermal resources without external energy input.
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 optimizes energy demand, reduces waste heat dissipation, and ensures passenger comfort by delivering heat at the required temperature level, extending the range of electric vehicles and reducing energetic losses.
Implementation Method 1
Heat is delivered from the coolant to the air to be conditioned by means of a heating heat exchanger of the HVAC system
Implementation Method 2
One of the partial air mass flows is directed through the heating heat exchanger and heated. The second partial air mass flow concurrently bypasses the heating heat exchanger
Data Source
AI summary
A method for operating an HVAC system includes the steps of adjusting a heating temperature of a heat exchanger disposed in a first flow passage, directing a first partial air mass flow through the first flow passage, directing a second partial air mass flow through a second flow passage, and directing the first partial air mass flow and the second partial air mass flow downstream of the first flow passage and the second flow passage, wherein the heating temperature of the heat exchanger required to at least one of achieve and maintain a desired climate in the passenger compartment of the vehicle is set as a maximum heating temperature for the heat exchanger, and wherein only an amount of energy required to at least one of achieve and maintain a desired climate in the passenger compartment of the vehicle is added to the HVAC system.