Solar hybrid air-conditioning design for buildings in hot and humid climates - Solar Energy Sciences and Engineering Applications - page 492

Figure 15.2.7 SHAC system with separate thermal and electrical energy sources.
15.3 PERFORMANCE EVALUATION OF VARIOUS SOLAR
AIR-CONDITIONING SYSTEMS
With the knowledge of different system configurations of solar air-conditioning
approaches, their cooling and energy performances for buildings in hot and humid
climates are of great interest. The operating energy would be determined for the var-
ious solar air-conditioning systems against conventional types, since energy saving is
the primary concern of any newly proposed air-conditioning (AC) system. As a start
to investigating solar air-conditioning systems in hot and humid climates, the study
area is subtropical Hong Kong (22.32 ◦ N, 114.17 ◦ E), using its weather data of the
typical meteorological year (Chan et al., 2006). In this section, we look at dynamic
simulation conducted for a typical office building zone (except Section 15.3.5 which
considers premises with high latent load), in which the ratio of the installed collector
area and the conditioned space is 1:2. A typical office has an area of 196 m 2 and an
occupant density of 8 m 2 /person. Daily occupancy is 10 hours between 8:00 a.m. to
6:00 p.m. The outdoor air amount is based on 0.01 m 3 /s/person. The lighting heat gain
is 17 W/m 2 (with 70% radiative) and the heat gain of office equipment is 230 W/person.
The fenestration to wall ratio is 0.5. Based on indoor design conditions of 25.5 ◦ C and
60% in relative humidity, the estimated design zone cooling load and ventilation load
are 20 kW and 9 kW respectively. The total net area of the solar collectors is 100 m 2
and the capacity of the hot water storage tank is 5 m 3 .
The system simulation model includes the appropriate control components, so
as to realize the dynamic interaction between the AC system and the building zone
under the changing loading and climatic conditions throughout a year. The solar air-
conditioning and the conventional AC systems are built using the validated component
models of the plant simulation program TRNSYS (SEL, 2006) and its associated com-
ponent library TESS (TESS, 2004). Meanwhile the dynamic component models of the
absorption chiller, the adsorption chiller and the desiccant wheel are specifically con-
structed according to those validated by Kim and Infante Ferreira (2008), Cho and
Kim (1992) and Zhang et al. (2003) respectively. Dynamic simulation is carried out to