Heat transfer coefficient is how easy the heat passes from one material to another, between solid and fluid or gas, air.
For example, the heat transfer coefficient for water is between 500 to 10,000 watts (meter square kelvin), air is 10 to 100 watts meter square kelvin.
SI unit of heat transfer coefficient is watts per squared meter kelvin. Other common units are btu per square feet fahrenheit and joule second per square meter kelvin
For heat capacity conversions please goto Heat Capacity
For heat flux density conversions please goto Heat Flux Density