On a summer day, the air temperature is 36°c and the relative humidity is 20%. water evaporates from the surface of a lake at a rate of 0.20 kg/h per square metre of water surface area. the temperature of water is 25°c.
(a) determine the mass transfer coefficient. (10 marks)
(b) determine the convective heat transfer coefficient. (10 marks)
(c) determine the net heat loss (in w/m2) from the lake. (5 marks)
the specific volume of water vapour at 25°c is 43.40 m3/kg and at 36°c is 23.97 m3/kg. the latent heat of evaporation at 25°c is 2441.8 kj/kg and at 36°c is 2415.8 kj/kg. the binary species diffusivity of water vapour in air is 26×10-6 m2/s. at 30.5°c, the density, constant pressure specific heat capacity and thermal conductivity of air are 1.177 kg/m3, 1.0049 kj/kg⋅k and 2.624×10-5 kw/m⋅k, respectively.