The heat capacity of humid air is approximately given by:
C p =1.005+1.82H
where 1.005 kJ/kg°C is the heat capacity of dry air, 1.82 kJ/kg°C the heat capacity of water vapor, and H is the absolute humidity in kg water vapor per kg dry air in the mixture. So the specific heat capacity of humid air is greater than dry air and humid air will take more energy to heat by a given amount.
But the difference is quite small. I think 100% RH at 25C is only about 2% water, and if you need to heat the room the temperature, and therefore the water content, is presumably even lower. Taking the 2% water content only increases the specific heat by about 3.6%.
CWatters said:Are you looking for the Specific Heat Capacity of humid air?...
Chestermiller said:You are forgetting about other, more important, heat transfer mechanisms like conduction and convection. In most practical situations, these will dominate over radiation.
AntiSpark said:If there are measurements or calculations to show how much they change (if any) depending on the amount of water vapor in the air? I'd take that as well.
But I was looking for how much the air would be warmed by IR radiation, and then that heat would be transferred by conduction and convection.
Seems as tho if I knew what amount of IR radiation would be absorbed by a sample of air that was 1% water vapor, that I would just double that to estimate it for 2% water vapor?
The thermal exchange rate of air, also known as the heat transfer coefficient, can be calculated by dividing the heat transfer rate by the difference in temperature between the two objects or mediums involved in the heat transfer.
The formula for calculating the thermal exchange rate of air is h = Q / (A * ΔT), where h is the heat transfer coefficient, Q is the heat transfer rate, A is the surface area, and ΔT is the temperature difference between the two objects or mediums.
The thermal exchange rate of air is typically measured in watts per square meter per kelvin (W/m²K) in the SI system. In some industries, it may also be measured in BTU per hour per square foot per degree Fahrenheit (BTU/hr·ft²·°F).
The thermal exchange rate of air plays a crucial role in determining the energy efficiency of a system or device. A lower thermal exchange rate means that less heat is lost or gained, resulting in improved energy efficiency.
The thermal exchange rate of air can be affected by a variety of factors, including the type of material used for the surface, the velocity of air flow, and the presence of any insulating layers. Additionally, the temperature and humidity levels of the air can also impact the thermal exchange rate.