Solar Hybrid Air Conditioner
Ahmad Hasan Abdalla, Didarul Islam, Saeed Al Khazraji
جامعة خليفة · الامارات
Given the extreme hot and humid ambient conditions of UAE, it comes no surprise that the demand for air conditioning would increase rapidly. In the UAE, roughly 90% of the electricity is consumed by the building sector. In that sector, air conditioners (A/Cs) consumes about 80% of the total annual house electricity. The fact that A/Cs perform efficiency decreases as the ambient temperature increases made issue more severe. Additional challenge to optimize energyconsumption is that in hot and humid regions A/C units are simultaneously required to control the temperature and humidity. In other words, the A/Cs electricity consumption will increase since they have to cool the incoming air more than needed in order to condense the water vapor. Thus, oversized A/C units are usually used which increases the energy consumption and affect indoor thermal comfort. Solar energy is an attractive solution to address the issue massive the electricity consumption of buildings. Such an alternative cannot be more applicable than the UAE given its high solar radiation. In addition, the cost of photovoltaic (PV) panels cost has been steadily decreasing recently. Consequently, this proposal presents an innovative solar hybrid A/C of a very high efficiency. The benefit results from innovative system integration of known technologies, building on the synergy derived from having each subsystem do what it can do best. The integrated system uses PV panels, a vapor compression cycle (VCC) for sensible load and a desiccant system for latent load. The proposed approach is based mainly on the concept of separate sensible/latent cooling (SSLC). This approach has been shown to allow the size of the VCC to be reduced since it only handles sensible loads. In addition, the lack of VCC operation's dependency on low temperature resulted in an increase of the VCC's coefficient of performance (COP). The systemutilizes thermoelectric device for the latent load to regulate the temperature of a new polymeric desiccant material. Both sub-systems can be powered by PV panels. The proposed solar hybrid A/C allows the independent control of temperature and humidity which improves comfort in conditioned spaces. The results for the maximum total load required for a standalone VCC is 70,990 Ton-hr. Therefore, ASHREA 55 optimization method was conducted which is considering 97% of the time of the year and excluding the extra cooling load in the 3%. Therefore, the optimized total load required was reduced to 69495 Ton-hr. The power reduction for each zone were summed up to 27%. Not only the power load was reduced, in addition the environmental impact caused by the system have also reduced by 776kg of CO2 emission. For the separate sensible latent cooling approach, the total sensible load required power by the VCC is 54,052 Ton- hr. However, the total latent load required power by the DCHX is 15,942 Ton-hr.