Space Cooling Using the Concept of Nanofluids-Based Direct Absorption Solar Collectors

Abstract

A solar-energy based vapor absorption refrigeration system is potentially an excellent alternative air-conditioning system. However, there are several research challenges to ensure sufficient efficiency and reliability for ensuring widespread implementation. Integration of a parabolic trough solar collector utilizing a mixture of nanoparticles and water with a vapor absorption system has the potential to significantly enhance the efficiency of the system. Such a system makes use of the superior thermo-physical properties of the nanofluid compared to the base fluid. Moreover, the direct absorption phenomenon of solar radiation through interaction with the participating medium (nanofluid) results in a higher temperature rise of the medium in conjunction with higher operating efficiencies as well. At the same time there are certain challenges that need to be identified and addressed in the implementation of this novel concept. For instance, to make it reliable, the system further needs to be integrated with a thermal storage system which facilitates air-conditioning even during non-sunshine hours. Integration of vapor absorption refrigeration technology, parabolic trough with water-nanoparticles mixture as the absorbing medium and a thermal storage facility is the uniqueness of this design which under certain conditions and locations may prove to be an efficient and reliable substitute to the conventional electrical air-conditioning systems. In this particular study a space cooling application for approximately 100 Tons of refrigeration is studied. Hourly variation in sunlight as well as seasonal changes for temperate climate conditions is considered. Parameters such as the cooling load of the space, and waste heat produced by electronics are evaluated. The cooling system driven by the nanofluid-based concentrated parabolic solar collector is mathematical modeled and then the optimization is done by varying the nanoparticle size and volume fraction in order to obtain the best result for collector outlet temperature, thermal efficiency and optical efficiency.

Direct absorption nanofluid-based solar collectors for low and medium temperatures. A review

“…The typical dimensions of the different families of medium-size solar collectors being consistent with the characteristic size of NDASC, the combination of these two technologies could thus provide a significant added value for SHIP applications over other competing technologies. To our knowledge, no studies addressed the integration of NDASC in SHIP applications, only few studies being dedicated to residential heating and cooling [135,172] or water desalination [173]. Future NDASC studies considering the working conditions of SHIP applications should be carried out to quantify the potential of concentrating NDASC in the industrial sector.…”

Enhancing the efficiency of absorption refrigeration cycle by ‘seeding’ nanoparticles directly in the working fluid

“…Recent studies by Khullar et al [8], Lenert et al [9] and Vishwakarma et al [10] show that adding nanoparticles to fluid flowing in a solar collector increases the efficiency of the collector by 5-10%. This is due to the scattering and absorption effects of nanoparticles according to the Mie scattering theory.…”