Fuel Cell Vehicle Cooling with Hot and Cold Thermal Buffers
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Solution Overview
Problem
Fuel cell electric vehicles (FCEVs) face challenges in efficiently managing cooling capacity, particularly due to the limitations of existing heat exchanger and fan systems, which result in increased energy consumption and reduced efficiency at higher heat loads.
Innovation Solution
The implementation of a cooling system that includes a 'hot buffer' and a 'cold buffer' within the vehicle, allowing for the controlled transfer of thermal energy between these buffers and the coolant circuit based on the ratio of cooling power to fan power. This system optimizes cooling capacity and energy efficiency by utilizing excess cooling capacity to charge the buffers and releasing stored cold energy when cooling capacity is insufficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a fan is used to increase cooling capacity of the heat exchanger, then cooling power is improved, but parasitic load and energy consumption increase
Solution Approach 1:
The invention stores cold thermal energy in advance during periods when cooling demand is low and cooling efficiency is high. This pre-stored cold energy is then utilized during periods of high cooling demand, eliminating the need to continuously operate the fan at high power levels and reducing overall energy consumption.
Solution Approach 2:
A thermal buffer chamber is introduced as an intermediary between the heat exchanger and the fuel cell cooling system. This buffer acts as a thermal reservoir that decouples the fan operation from immediate cooling demands, allowing the fan to operate more efficiently while the buffer smooths out thermal fluctuations.
2Power
If fan power is increased to meet higher heat loads, then cooling capacity is improved, but cooling efficiency decreases
Solution Approach 1:
The system performs preliminary cooling action by storing cold thermal energy in the buffer chamber during periods when the cooling system operates efficiently. This pre-cooled energy is then released during high heat load periods, maintaining high cooling efficiency even when overall cooling capacity needs to be increased.
Solution Approach 2:
The cooling system operates in periodic cycles, alternating between charging the thermal buffer when conditions are favorable (high efficiency) and discharging the buffer when cooling demand exceeds immediate capacity. This periodic operation optimizes the average efficiency of the cooling system.
3Reliability
If the cooling system operates continuously at high capacity, then cooling performance is maintained, but energy consumption increases
Solution Approach 1:
The thermal buffer is charged in advance during periods of low cooling demand or high cooling efficiency, storing cold thermal energy that can be rapidly discharged when cooling performance is immediately needed, thereby maintaining reliable cooling performance without continuous high-energy operation.
Solution Approach 2:
The thermal buffer serves the cooling system by providing supplemental cooling capacity during peak demands, reducing the need for the fan and heat exchanger to operate at maximum capacity continuously. The buffer essentially services the cooling system's peak requirements independently.
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 enhances the cooling capacity and energy efficiency of the vehicle by effectively utilizing excess cooling energy to charge thermal buffers, which can then be discharged during periods of insufficient cooling capacity, thereby reducing the power required to operate the cooling system.
Implementation Method 1
a heat exchanger for cooling the circulating coolant
Implementation Method 2
A fan may be placed behind the heat exchanger to increase the cooling capacity of the heat exchanger by driving ambient air through the heat exchanger
Implementation Method 3
control thermal energy transfer between the coolant and said chambers based on said ratio
Data Source
AI summary
A cooling system in a fuel cell electric vehicle comprising a first chamber configured to contain relatively hot fluid and a second chamber configured to contain relatively cold fluid. The ratio of cooling power/fan power of a positive displacement device at a heat exchanger is monitored and thermal energy transfer between coolant and the chambers is controlled based on the ratio. When the ratio is above a pre-defined value or value range, thermal energy from the first chamber is provided to the coolant in the coolant circuit and passed into the heat exchanger, after which part of the thermal energy of cooled coolant leaving the heat exchanger is provided to and stored in the second chamber. The stored cold thermal energy is released from the second chamber when the ratio is below the pre-defined value or value range. The invention also relates to a method of controlling a cooling system.