Passenger Vehicle AC Venting for Refrigerant Leak Protection
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Solution Overview
Problem
The use of refrigerants that pose a risk to human health in passenger transport vehicles' air conditioning units, such as propane, requires measures to safely manage leaks to prevent exposure to passengers.
Innovation Solution
A degassing device is integrated within the air conditioning unit, fluidically separating cooling and supply air channels with a closable partition wall, equipped with a detector that initiates the degassing device's open state upon refrigerant detection, allowing the condenser fan to draw in and discharge contaminated supply air to the environment, assisted by throttling or shutting down the supply air fan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If alternative refrigerants with increased risk to human health (e.g., R290 propane) are used in the refrigeration circuit, then environmental friendliness and energy efficiency are improved, but the risk of explosion or asphyxiation to passengers increases
Solution Approach 1:
The air conditioning unit is divided into separate flow channels: a first flow channel for cooling air and a second flow channel for supply air, separated by a partition wall. This segmentation prevents refrigerant-laden supply air from entering the passenger compartment under normal conditions while allowing independent control of each air stream.
Solution Approach 2:
A degassing device is introduced as an intermediary element in the partition wall between the two flow channels. This device acts as a controlled interface that remains closed during normal operation but can be opened to vent refrigerant-laden air from the supply air channel to the cooling air channel, which is then discharged safely to the environment.
2Ease of operation
If the degassing device is kept closed to maintain normal air conditioning operation, then passenger comfort is preserved, but refrigerant leaks cannot be vented safely
Solution Approach 1:
A detector is installed in the supply air channel to monitor for the presence of refrigerant. When refrigerant is detected, the detector sends a signal to the control device, which then actuates the degassing device to open and vent the refrigerant-laden air, creating a closed-loop feedback system that responds automatically to leak conditions.
Solution Approach 2:
The degassing device is pre-positioned in the partition wall and can be rapidly actuated from closed to open state when needed. The control device is pre-configured to receive signals from the detector and immediately open the degassing device upon refrigerant detection, eliminating delay between detection and protective action.
3Productivity
If the supply air fan continues to operate at full speed to maintain air flow, then cooling performance is maintained, but refrigerant-laden air is pushed into the passenger compartment
Solution Approach 1:
The supply air fan speed is made dynamic rather than fixed. The control device adjusts the fan speed based on operating conditions: during normal operation the fan runs at standard speed for optimal cooling performance, but when refrigerant is detected and the degassing device opens, the fan speed is reduced or shut down to prevent pushing refrigerant-laden air into the passenger compartment.
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
Effectively reduces the risk to passengers by safely venting refrigerant-laden air outside the vehicle during leaks, ensuring passenger safety even with hazardous refrigerants like propane.
Implementation Method 1
the Bernoulli effect occurs in the region of the degassing device, which leads to the supply air located in the supply air channel, which in the event of a leak is loaded with refrigerant, being drawn in
Implementation Method 2
there is provided a detector for the refrigerant which is connected via signals to the degassing device such that, when it detects the refrigerant, it initiates actuation of the degassing device
Data Source
AI summary
A passenger transport vehicle contains an air conditioner which has a refrigerant circuit operated using a refrigerant. The refrigerant circuit has a condenser with a fan for conveying cooling air and an evaporator for controlling the temperature of supply air conveyed by a supply fan into a passenger compartment. Flow ducts for the cooling air and for the supply air are fluidically separated from one another inside the air conditioner by a partition wall. The partition wall has a degassing device being switched between a closed state for normal operation of the air conditioner and an open state for emergency operation of the air conditioner, in which emergency operation the degassing device fluidically connects the flow duct for the cooling air and the flow duct for the supply air to one another. A refrigerant detector is provided and when it detects the refrigerant, it triggers actuation of the degassing device.