Theoretical and Experimental Study of a Novel Film Evaporation Cooling System

Abstract

A novel cogeneration cooler is presented in this paper. The entered air cools in two streams. In the first stream, air goes into the channels and cooling happens without increasing humidity. The second stream is the air flow that goes out of the channels on the water film and cooling happens with increasing of humidity. Both of the two cooled air is useful, but for different places in one building. The film evaporation cogeneration cooler with its’ two new idea can save considerable amount of energy. Production of cooled air with evaporation of water film from surface of aluminum channels and production of humid and non-humid cooled air in this cooler are two helpful ideas that theoretical and experimental calculations approve the practicability of ideas. The results show that this novel cooler has high COP and in the cases that both of its cooled air production can be useful, it has so high performance and can conserve much energy.

Nomenclature

c_p :

Specific heat, J kg^-1 °C^-1

D:

Mass diffusivity, m² s^-1

g:

Gravitational acceleration, m s^-2

h:

Heat transfer coefficient, W m^-2 °C^-1

k:

Conduction coefficient

l:

Length, m

m:

Mass rate, kg s^-1

M_v :

Molecular weight, kg mol^-1

Nu:

Nusselt Number

P_v,i :

Vapor pressure, Pa

Q:

External heat flux of wetted wall, W m^-2

Re:

Reynolds number

T:

Absolute temperature, K

u_G :

Axial velocity, m s^-1

v_G :

Transverse velocity, m s^-1

w:

Mass fraction

λ:

Thermal conductivity of the fluid, W m^-1 K^-1

μ:

Dynamic viscosity of the fluid, kg m^-1 s^-1

Cond:

Conduction

Conv:

Convection

f:

Surrounding fluid

G:

Gas flow

L:

Water film

v:

Vapor