Q8Electrical Machine Design
Question
Q.8. The density of hydrogen as compared to air is (given numeral value).
Answer
The density of hydrogen compared to air is approximately 0.07 (about 7% of air's density), making hydrogen roughly 14 times lighter than air.
The relative density of hydrogen compared to air is approximately 0.0696, commonly rounded to about 0.07 (i.e., hydrogen is roughly 1/14th as dense as air). This very low density, combined with hydrogen's high specific heat and thermal conductivity (about 7 times that of air), is precisely why hydrogen is used as a cooling medium in large turbo-generators — it produces much lower windage losses than air while removing heat far more effectively for a given coolant flow, which is why hydrogen-cooled turbo-generators achieve significantly higher output ratings for a given frame size than air-cooled equivalents.