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abstract This paper presents the characterization and the pre-dimensioning of an adsorption chiller as part of
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a 20 kW air conditioning central unit for cooling a set of rooms that comprises an area of 110 m2
. The system is basically made up of a cold water storage tank supplied by an activated carbonemethanol
adsorption chiller, a hot water storage tank, fed by solar energy and natural gas, and a fan-coil. During an
acclimatization of 8 h (9e17 h), the following parameters were obtained for dimensioning the cooling
system: 504 kg of activated carbon, 180 L of methanol, 7000 L of hot water, 10,300 L of cold water with its
temperature varying in the fan-coil from 1 Cto14 C. Considering the mean value of the total daily
irradiation in João Pessoa (7 and a cover of regenerating heat supplied by solar energy 5029
equivalent to 70%, the adsorption chiller’s expected coefficient of performance (COP) was found to be
around 0.6. 2010 Elsevier Ltd. All rights reserved.1. Introduction
Solar cooling is an interesting application of solar energy because,
the stranger the insolation, the greater needs for cooling. As a rule,
the systems requiring thermal energy as theirmain power input for
the production of frigorific effect are most dependable on sorption
processes. The use of solar energy for cooling applicationsea device
based on the liquid sorption cycle e was reported more than forty
years ago by Chinnappa [1].
The energy needed for a sorption cooling system is essentially
thermal, and may come from different sources, such as: process
heat, residual vapor or solar energy. One of the main advantages of
such a system in relation to the conventional vapor compression
system lies on its minimum use of electric energy and on its low
cost of maintenance.
Because of its functioning simplicity, the adsorption technology
applicable to refrigerating systems differs significantly from that of
absorption. In adsorption there occurs an interaction between
a solid and a fluid e the transportation of the latter being
a dependable thermal gradient, for it does not require the use of
pumps. In the case of absorption, a solution interacts witha refrigerating fluid, calling for a number of electromechanical
devices so as to move both the solution and the fluid.
Moreover, the adsorption cycle depends on fewer electrome-
chanical components (heat exchangers, valves). Conversely,
adsorption refrigeration has exhibited performance coefficients
lower than those obtained by liquid absorption. In the field of solar
refrigeration by adsorption, various kinds of solid pairs have been
considered; zeoliteewater [2,3] and silica gelewater [4,5] are used
for cold storage, whereas activated carbonemethanol [6,7] and
activated carboneammonia [8,9] are used for ice production.
A comparative study between the liquid, chemical reaction and
adsorption cooling systems was published by Meunier [10]. In all
these systems, the mechanical energy consumption is kept to
a minimum or null. This represents a great advantage over the
conventional vapor compression systems, especially in countries
like Brazil whose energy consumption depends heavily on hydro-
electric power.
Solar energy is abundant over large areas in Northeastern Brazil
(annual average being over 6 kW/m2
day), securing, as a result,
a great potential supply for use in helio-thermal conversion
systems applicable for both heating and cooling purposes. Many
farm and fishing products are lost in this region, mainly because of
unsatisfactory refrigeration, or otherwise, these products have their
final value decreased for lack of economical frigorific preservation.
In the last two decades, absorption chillers, running on natural