ZEMCH 2015 - International Conference Proceedings | Page 687

Li et al. 2006:1-8). It also rises with a cylindrical or elongated shape of the nanoparticles instead of
spherical particles (Murshed et al. 2005:367-373; Xie et al. 2002:571-580) and with a decrease of base
fluid thermal conductivity (Xie et al. 2002:1469-1471). Some studies show that the use of nanofluids
in solar collector can improve the outlet temperature and efficiency; one of these (Yousefi et al.
2012:293-298) investigated experimentally the effect of Al2O3–water nanofluid as working fluid on
the efficiency of a flat-plate solar collector, showing an increasing of the efficiency up to 28.3%,
for a 0.2% volume fraction and an enhancement of 15.63% in heat transfer efficiency due to the
surfactant. They (Yousefi et al. 2012:207-212) also studied the efficiency of a flat-plate solar collector
with MWCNT nanofluid as working fluid, deducing an increasing of the efficiency only adding a
surfactant. Another study (Colangelo et al. 2013:80-93) reported the experimental results and the
potential performance of the investigation on flat solar thermal collectors using nanofluids and
it showed a thermal conductivity enhancement up to 6.7% at a concentration of 3.0 vol% of Al2O3
nanoparticles. They also measured an increase of thermal efficiency up to 11.7% by using nanofluid instead of water as working fluid in a modified flat panel solar thermal collector (Colangelo et
al. 2015:874-881). More studies have been made about the effect of using different kinds of nanofluid on the efficiency of direct absorption (Parvin et al. 2014:386-395; Tyagi et al. 2009:1-7; Otanicar
et al. 2010:033102; Saidur et al. 2012: 5899-5907), evacuated tubes (Lu et al. 2011:379-387; Liu et al.
2013:135-143), transparent parabolic trough (de Risi et al. 2013:134-139) and concentrated parabolic
solar collectors (Lenert et al. 2012:253-265; Khullar et al. 2013:1003-1012).

Description of the case study
The case study analyses two different simulation models of solar cooling system designed to air
condition a hypothetical detached building located in Brindisi, Italy, in a time range starting on
the 1st June and ending on the September 30. The performance of the solar cooling system is
defined using TRNSYS 16, a transient systems simulation program with a modular structure. The
environment internal time step used was 1 hour. The chilled water system for TRNSYS simulation
is consisting of the following elements:
Single-family residential building (Type 660).
A volume of conditioned air of 1000 m3 has been chosen. Internal loads through persons depend
on four occupants from 8:00PM to 8:00AM, three occupants from 12 noon to 3:00PM and two occupants from 3:00PM to 8:00PM. Lighting loads are included from 6:00PM to Midnight.
Solar collector field (Type 1).
Solar collector field – WATER:
• Flat plate collector field has an area of 25 m2;
• The flow rate per unit area at which the collector was tested in order to determine the collector
efficiency parameters = 0.02 kg/s*m2;
• Intercept efficiency, in equation form, this parameter is a0 in the collector efficiency equation:
(1)

and it is equal to 0.517;
• Efficiency slope, in equation form, this parameter is a1 in the equation and it is equal to 4.452
W/m2*K.

Dynamic simulation of a solar cooling HVAC system with nanofluid

685