# Dunkle rsquo s model Chen

Fig. 35. Schematic of the solar still coupled with Bay 36-7620 heat pump [42].Figure optionsDownload full-size imageDownload as PowerPoint slide

The energy balance for the glass cover is given byequation(270)mgCgdTgdt=(1−Rg)αgI(t)h+(qc,w−g+qe,w−g+qr,w−g)−qr,g−a−qc,g−a

The energy balance for the evaporator is given byequation(271)mevCevdTevdt=qc,w−ev+qe,w−ev−qe,ref

The energy balance for the basin water is given byequation(272)mwCwdTwdt=(1−Rg)(1−αg)αwI(t)h−(qc,w−g+qe,w−g+qr,w−g)AgAw+qw+WAw

The energy balance for the absorber is given byequation(273)mbCbdTbdt=(1−Rg)(1−αg)(1−αw)αbI(t)h−qw−qloss

The condensation rate is given byequation(274)dmewdt=Awqe,w−g+Aevqe,w−evAwhfg

A computer simulation program based on the energy and mass balance equations was developed to investigate the performance of the solar still and the effect of the various design as well as the operating parameters that affect productivity. In this simulation program, energy and mass balance equations were solved simultaneously by using the fourth order Runge–Kutta method. The initial temperatures values of the system components were assumed to be approximately equal to ambient temperature.