At the recently held Annual Middle East District Cooling Summit in Doha, QPM corporate sustainability director Salah Nezar addressed the fact that the HVAC (heating, ventilating, and air-conditioning) industry in Qatar was searching for a scalable and affordable cooling solution to provide comfortable outdoor environments during the summer months (from April to October).
Nezar highlighted the approach used by a team of researchers in mitigating engineering challenges related to a proposed solution co-authored by him in partnership with Dirk Krüger and Jürgen Dersch from the German Aerospace Centre (DLR).
Nezar said: “The need for a comfortable outdoor environment is led by local community lifestyles and the business segment of the hospitality sector, where priorities include public areas such as walkways, playgrounds, seating/dining areas associated with coffee shops, restaurants and souqs, as well as the general outdoor sporting and leisure venues.
“In a region where sedentary lifestyles are at the heart of acute public health issues such as obesity, diabetes, decline in fertility rates, vitamin-D deficiency and respiratory ailments such as asthma, a viable outdoor cooling solution will promote
overall health, fitness and strength of the local community.”
The components of the proposed solution include air and chilled water systems. A solar field and its ancillary components will power the thermally driven cooling machine and associated thermal storage tank to optimise the performance of the chilling system.
The engineering efforts related to this part of the proposal were led by the team from the DLR with a focus on optimisation of the solar field, including the suitability of each type of the proposed solar collectors and level of energy
performance expected.
The second segment of this research effort was oriented towards integrating various components pertaining to the solar and cooling system into a single system capable of operating at the highest efficiency level and by upholding cutting-edge clean technologies.
The air system part of the solution was handled by a local team in collaboration with an HVAC expert from California. The design approach is built on the “Sunken Garden” concept traditionally used in the Middle East to contain colder air. The accompanying air handling system is a two-stage evaporative cooling machine.
Nezar said: “The economic and financial analysis of the proposed solution was performed by the DLR team in close collaboration with a local team. The cost of a conventional cooling system equals €0.12/kWh.”
The findings showed that the initial design has a number of limitations from an engineering standpoint and also has low economic performance as the cost of cooling energy was found to be around €0.35/kWh.
As part of the evolution of the project, a number of design modifications were introduced into the simulation process to improve the cost-effectiveness of the solution, including the decrease of the solar share ratio to 90%. Refined economic analysis showed that the cost of cooling energy could reach €0.2/kWh if the surplus heat energy produced by the solar field could be utilised or absorbed adequately by another system or facility at periods when it is not required by the cooling machine.
Nezar and the team submitted a full paper for international peer review and it will be presented to an international panel of experts by the end of the November in Paris for proof of concept and economic viability.
The team will soon embark on proving their findings through a reduced scale modular prototype. The realisation of the prototype was undertaken by a Saudi investor who pledged to invest in the development and commercialisation of the solution for various applications, including in the field of oil and gas.
