Experimental comparison of two solar-driven air-cooled LiBr/H2O absorption chillers: Indirect versus direct air-cooled system

• Indirect and direct air-cooled LiBr–H2O absorption technology is compared.
• First time this comparison is made experimentally.
• The power source was a field of flat panel vacuum solar collectors.
• The outdoor dry bulb temperatures from 28 to 37.7 °C.
• With the direct system higher tig, lower toe and higher COP are obtained.

Experiments were run to compare an indirectly air-cooled commercial absorption chiller to a directly air-cooled absorption chiller prototype. Both were 4.5-kW, 1-m3, single-effect LiBr–H2O chillers. The trials were conducted at outdoor dry bulb temperatures ranging from 28 to 37 °C. The maximum allowable generator inlet temperature in the commercial chiller (to prevent salt crystallisation) was 105 °C, while in the prototype it was 120 °C. The commercial chiller delivered chilled water at 18 °C and the prototype at 16 °C. The mean daily COPth was 0.55 in the commercial chiller, compared to 0.62 in the prototype. The mean daily COPelec for the chiller and prototype was 3.5 and 5.3, respectively. The mean daily SCOP for the solar-powered air conditioning facility was around 0.08 in both cases.