Heat Management Flashcards
Roughly how much waste heat is produced in a PEMFC?
50% of the power created is waste heat.
What are the main sources of heat management?
Radiators and intercoolers.
Describe the radiator system.
Run deionised water.
Stainless steel needed rather than aluminium.
Need an intercooler and compressor included in the system.
Why is deionised water used in radiators?
It is not electrically conductive.
What temperature difference can be present across a stack?
10 degrees.
What temperature range does a stack operate in?
65 - 90 degrees.
How does temperature affect voltage loss in a cell?
Ionic resistance is temperature dependent and is the main source of resistance, so Vohmic.
How can a polarisation curve show waste heat?
Everything above the curve is heat produced, everything below is electrical.
What part of the cell is used for heat management?
The bi-polar plate.
What are the three main types of cooling used across fuel cells?
Cathode Air Cooling
Isolated Air Cooling
Liquid Cooling
What is the most common cooling method used for PEMFC within aeronautical and HGV automotive applications?
Liquid cooling is preferred for high power applications.
Why is air cooling not used for high power applications?
Because the rate at which the air would be pumped could dry out the fuel cell, decreasing the RH value.
The efficiency of liquid cooling for these applications is preferred.
