Solar Energy

Topics: Photovoltaics, Energy, Concentrating solar power Pages: 27 (3418 words) Published: December 5, 2013
Solar Energy 77 (2004) 311–318
www.elsevier.com/locate/solener

A new solar powered adsorption refrigerator
with high performance

Meunier published a comparison of those three sorption
systems for solar cooling (Meunier, 1994). The solid–gas
system used in the present study is adsorption.
The solar adsorption refrigerators have been developed mainly to be used in hot regions with no electricity supply. There is an urgent need in the health sector (for
the conservation of medicines and vaccines). These systems have the advantage of not requiring any energy other than solar energy.

Nomenclature
COP
Cp
G
H
L
m
n
P
Q
A
T
t

coefficient of performance [–]
specific heat [J kgÀ1 KÀ1 ]
global irradiance [W mÀ2 ]
global irradiation [J]
evaporation latent heat for water [J kgÀ1 ]
mass [kg]
number [–]
pressure [Pa]
heat quantity [J]
area [m2 ]
temperature [K]
time [s]

d
e
fs
h
l
L
m
N
R
S
tl
w

day
evaporator
collector front side
solar heat supply
load
liquid
maximum
net
rough
solar
thermal losses (of the cabinet)
water

Indexes
c
condenser

Guilleminot, 1986; Pralon Ferreira-Leite and Daguenet,
2000) using either a chemical reaction or adsorption,
follow an alternative cycle of heating/cooling, also
known as ‘intermittent’, the period of which corresponds to the alternation of day and night.
Regarding performance, the highest values of COPSR
(0.10–0.12) were obtained with the adsorption systems
zeolite + water (Grenier et al., 1988) and activated carbon + methanol (Boubakri et al., 1992a,b; Pons and Grenier, 1987). As methanol can easily evaporate at
temperatures below 0 °C, thus favouring the production
of ice, the most environmentally friendly refrigerant must
be water. Using water, ice can be produced within the
evaporator, acting as a ‘cold storage’. Both refrigerants, water or methanol, operate at below atmospheric pressure and therefore require vacuum technology. The main purpose of the present study is to obtain

better performances than those reported above, with
what is, technically speaking, a simple machine. This
aim seems reasonably achievable with an adsorptive
machine, operated in a 100% solar-powered 24 h cycle
with a flat-plate solar collector containing the adsorbent. However, when referring to the work reported above,
both the efficiency of the solar collector and that of the
adsorption thermodynamic cycle could be improved.
These requirements were crucial to the design of the
‘advanced’ machine.
The laboratory of solar energy of the Engineering
school of the Canton de Vaud (EIVD, Yverdon-lesBains, Switzerland) has been developing adsorptive solar refrigerators since 1999. The first systems built used the
adsorption pair of activated carbon + methanol. For
reasons of reliability and respect for the environment,
this pair has been abandoned in favour of a silicagel + water pair.

The prototype described and analyzed in this paper
has been functioning since the summer of 2000 on the
site of the EIVD. A thorough measurement system allows us to characterise it in a complete way. During the summer of 2001, a constant procedure of thermal load in
the cold cabinet allowed us to observe the behaviour of
the adsorption system over a continuous period of 68
days. We have highlighted the great influence of both
external temperature and daily irradiation upon the
daily coefficient of performance (COPSR ). Previously,
few articles were interested in the analysis of the storage.

2. Description of adsorption and of the adsorption cooling
cycle
Adsorption, also known as physisorption, is the
process by which molecules of a fluid are fixed on the
walls of a solid material. The adsorbed molecules undergo no chemical reaction but simply lose energy when being fixed: adsorption, the phase change from fluid to
adsorbate (adsorbed phase) is exothermic. Moreover
this process is reversible. In the following, we will focus
on adsorption...

References: Boubakri, A., Arsalane, M., Yous, B., Ali-Moussa, L., Pons,
M., Meunier, F., Guilleminot, J.J., 1992a
Boubakri, A., Arsalane, M., Yous, B., Ali-Moussa, L., Pons,
M., Meunier, F., Guilleminot, J.J., 1992b
Buchter, F., Hildbrand, C., Dind, Ph., Pons, M., 2001.
Buchter, F., Dind, Ph., Pons, M., 2003. An experimental solarpowered adsorptive refrigerator tested in Burkina-Faso.
Chinnappa, J.C.V., 1962. Performance of an intermittent
refrigerator operated by a flat-plate collector
Critoph, R.E., 1994. An ammonia carbon solar refrigerator for
vaccine cooling
Critoph, R.E., Tamainot-Telto, Z., Munyebvu, E., 1997. Solar
sorption refrigerator
Erhard, A., Spindler, K., Hahne, E., 1998. Test and simulation
of a solar powered sorption cooling machine
Grenier, Ph., Guilleminot, J.J., Meunier, F., Pons, M., 1988.
Headley, O.StC., Kothdiwala, A.F., McDoom, I.A., 1994.
Liu, Z., Lu, Y., Zhao, J., 1998. Zeolite-active carbon compound
adsorbent and its use in adsorption solar cooling tube
Marmottant, B., Mhimid, A., El Golli, S., Grenier, Ph., 1992.
Meunier, F., 1994. Sorption solar cooling. Renewable Energy 5
(1), 422–429.
Mhiri, F., El Golli, S., 1996. Etude d’un r frig rateur solaire
e e
Pons, M., Guilleminot, J.J., 1986. Design of an experimental
solar-powered, solid-adsorption ice maker
Pons, M., Grenier, Ph., 1987. Experimental data on a solarpowered ice maker using activated carbon and methanol
adsorption pair
Pralon Ferreira-Leite, A., Daguenet, M., 2000. Performance of
a new solid adsorption ice-maker with solar energy regeneration
Spinner, B., Goetz, V., Mazet, N., Mauran, S., Stitou, D., 1999.
Worsøe-Schmidt, P., 1983. Solar refrigeration for developing
countries using a solid absorption cycle
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