Solar hybrid air-conditioning design for buildings in hot and humid climates - Solar Energy Sciences and Engineering Applications - page 486

2010). Solar-thermal desiccant cooling systems with appropriate auxiliary heating can
be operated during both daytime and night-time (Enteria et al., 2009). New system
design and material for solar desiccant cooling was proposed to enhance its energy per-
formance (Ge et al., 2010). The design and operation of a solar air-conditioning system
using parabolic solar collectors and double-effect absorption chiller was evaluated for
the application in a conditioned space (Qu et al., 2010). By combining an ejector cool-
ing system and an inverter-type heat pump, a prototype of a hybrid solar cooling and
heating system was designed and constructed (Huang et al., 2010). The energy and
economic feasibility of a solar air-conditioning system for buildings in temperate and
Mediterranean climates has also been evaluated (Calise, 2010).
In this chapter, Section 15.2 discusses the possible design approaches and features
of solar air-conditioning. Section 15.3 presents the cooling and energy performances of
the various solar air-conditioning systems, including the principal systems and different
hybrid designs. Section 15.4 demonstrates the application potential of solar hybrid
air-conditioning (SHAC) in the various hot and humid cities in Southeast Asia. In
conclusion, Section 15.5 looks at future development.
15.2 DESIGN APPROACHES OF SOLAR AIR-CONDITIONING
In the context of solar air-conditioning, various types of solar collectors, refrigeration
and air-conditioning cycles are interlinked or hybridized so that the indoor design
conditions of the buildings can be fulfilled throughout the year. Solar air-conditioning
can be developed in the following four approaches according to system complexity, as
consolidated in Figure 15.2.1.
In any one of the design approaches, electricity is still required to drive the par-
asitic equipment - such as pumps, fans and cooling towers - of the various solar
air-conditioning systems. In the study of solar air-conditioning systems, it is necessary
to take a holistic view of the energy consumption of all the equipment involved.
15.2.1 The solar-electric approach
Photovoltaic (PV) panels are used to generate electricity, which can be in turn be
used to drive conventional vapour-compression refrigeration. The compression chiller
driven by direct current can also be considered in order to prevent losses from current
conversion. Both roof-mounted and building-integrated strategies can be applied for
the installation of PV panels. In this approach, an auxiliary electricity supply, generally
from the power grid, is required in case of electricity deficit to the solar-electric air-
conditioning system. Although it is relatively straightforward to apply the conventional
monocrystalline and polycrystalline PV panels for driving the compression chiller, their
environmental impacts from production and disposal have been the subject of study in
recent years (Gottessfeld and Cherry, 2011; EC, 2011), apart from the new thin film
PV which is technologically mature enough to supersede the crystalline types.
15.2.2 The solar-thermal approach
Solar-thermal collectors, like flat-plate collectors, evacuated tubes or parabolic con-
centrators, are applied to generate heat for the thermally driven refrigeration or