The Undergraduate Research Competition (URC) is one of the largest competitions in the GCC that promotes scientific research among undergraduate students and supports the UAE government’s initiative of fostering innovation and empowering the youth to prepare them for the future. This is the eighth year of the competition and the research event has attracted creative minds not only from the GCC but in other countries as well such as Indonesia, Malaysia, Malta, and Morocco.

Around 315 original research papers were presented from 87 major universities in different disciplines, including engineering, natural and health sciences, business administration, education and law, and arts and social sciences.

The Chemical Engineering senior project of Khalifa University students Muna Al Jasmi, Anfal Abloushi, Shamma Thani, Reem Saeed Salem, and Ali Ahmed Algallaf, supervised by Prof. Lourdes Vega and Dr. Daniel Bahamon, won second place in the Chemical and Petroleum Engineering Category of the competition, with the project titled “Design of an Adsorption Air-Conditioning System Using Low Global Warming Potential (GWP) Refrigerants.”

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“This system is the first of its kind in the region and considered as one of the most promising technologies because of its advanced features as it does not depend on the electric energy generated from fossil fuels. It can work using electricity from renewable sources and a great alternative from an economical as well as environmental point of view,” Muna said. She explained that the system uses water as the refrigerant that provides powerful cooling while at the same time offers a sleek design that incorporates simple construction, easy control, quiet operation with no vibration, and low maintenance.

Cooling systems are an essential technology in our life, especially in arid and semi-arid regions, like the UAE.

“Current air-conditioning and refrigeration systems are energy-intensive, consuming around 17 percent of the global electricity production and more than 60 percent in the Emirates, representing a major impact on global warming and climate change. Moreover, the primary refrigerants used today have a high global warming potential (GWP), being thousands of times more potent greenhouse gases than carbon dioxide. Hence, active work is needed to replace them with low GWP refrigerants and to find more efficient cooling equipment. In their research project, our group of students proposed and designed an adsorption refrigeration system as an alternative to the compression system using water as the refrigerant, a silica-gel as the adsorbent, and a solar collector to provide the heat source to operate the system, a creative system with much lower impact into the environment than the ones currently used, representing a step forward on solving this very important environmental issue,” Dr. Vega said.��

“Obtaining second place in such a strong competition is a well-deserved recognition of their hard and innovative work and we are so proud of them!” she added.

The design the team came up with can be used here in the UAE and in other countries with similar weather conditions.��

“This project gave us an opportunity to apply the chemical engineering knowledge we gained during our academic journey to find and implement a solution to a major climate dilemma. We expect that in the near future, these novel technologies will change the whole scenario of sustainability, and will position the UAE to become a pioneer in the field of the new green economy globally,” Muna added.

Dr. Fawzi Banat, Professor and Chair of the Chemical Engineering Department, commented, “In the Shanghai Global Ranking of Academic Subjects 2021, which is dedicated to academic institutions for teaching and research, the Department of Chemical Engineering is ranked among the top 76-100. To achieve this ranking, the department achieved high scores on all of the analyzed indicators, which include articles indexed in Web of Science, the total number of citations, citations per article, articles published in the top 25% of scientific journals, and international interaction developed through collaborations with foreign institutions.”

“The department is dedicated to research and teaching excellence and currently offers doctoral, master’s, and bachelor’s degrees,” Dr. Banat added.��

The UAE actively supports a knowledge-based economy transformation, and events such as the URC encourages students to be more involved in accelerating the research needed to drive innovation in the country.

Ara Maj Cruz
Creative Writer
5 August 2021

The post Research on Sustainable Refrigeration System Nabs 2nd Place Win at the 8th Undergraduate Research Competition appeared first on Khalifa University.

As global energy demand from air conditioners continues to rise, finding a way to replace energy-intensive systems is paramount.

Read Arabic story .

As the mercury rises in the UAE, Dr. Lourdes Vega, Director of the Khalifa University Research and Innovation Center on CO2 and hydrogen (RICH), and KU Research Scientists Dr. Edder Garcia and Dr. Daniel Bahamon are turning their attention to finding efficient and environmentally-friendly forms of air conditioning systems.

“Due to global warming and a boost of wealth in tropical regions, the demand for refrigeration and air-conditioning is likely to increase in the coming years,” explained Dr. Vega. “This process already accounts for around 10 percent of the global electricity consumption, so finding green alternatives is of utmost importance.”

Global energy demand from air conditioners is expected to triple by 2050, and supplying power to these AC units comes with large costs and environmental implications.

Dr. Vega and her team are investigating a cleaner cooling process known as ‘absorption refrigeration,’ which could replace conventional energy-intensive vapor compression refrigeration, and could even be used as a way to store solar energy.

Conventional AC systems rely on vapor-compression cycles and a mechanical compressor. This is how it works: Refrigerant flows through a compressor, where it gets pressurized. Then the refrigerant flows through a condenser, where it condenses from vapor form to liquid form, giving off heat in the process. From the condenser, the refrigerant goes through an expansion valve and its pressure drops. Finally, the refrigerant travels to the evaporator, where it draws heat from the air around it (the air that needs to be cooled), which causes the refrigerant to vaporize. The vaporized refrigerant then goes back to the compressor to restart the cycle. In addition to the electricity consumption associated with air conditioning, in current vapor-compression cycles the refrigerant is usually a fluorinated gas (F-gas) with high global warming potential, making the phase out of such gases an urgent environmental need.

An adsorption-based refrigeration system is much simpler. It has two main components: a tank, where the liquid refrigerant is stored, and a bed filled with a solid material known as an ‘adsorbent.’ The refrigerant molecules ‘adsorb’, or attach, onto the surface of this material instead of dissolving into a liquid, creating a film on the surface where refrigerant vapor accumulates.

The adsorbent is a highly porous material with a large internal surface, full of holes that collect the refrigerant vapor. These systems transform energy into cooling power without any moving parts, making them low maintenance and more durable than conventional vapor-compression refrigeration systems.

Importantly, adsorption refrigeration can be powered by renewable energy sources, like the sun.

During energy production peaks, such as during the middle of the day for solar power supplies, heat is transferred to the adsorbent, causing the refrigerant to vaporize and desorb from the solid adsorbent. It detaches from the pores in the adsorbent and is condensed into a liquid for storage in the tank.

When it is time to cool down the air outside the unit, the liquid refrigerant is released to the evaporator, removing a heat from the surrounding area.

“When the refrigerant adsorbs onto the solid surface adsorbent, energy is released,” explained Dr. Vega. “Therefore, the adsorbent can be used as a thermal energy storage unit. Energy is stored during the removal of the refrigerant from the adsorbent material. The stored energy is recovered during the adsorption step and can be used as a low-temperature energy source. In this way, we can make a unit that both cools the air and stores energy.”

Developing such a unit however requires finding the perfect adsorbent-refrigerant pair. Currently, the most common refrigerants for domestic and automobile air conditioning and for vapor-compression cycles are hydrofluorocarbons, but these have tremendous global warming potential and are being phased out globally.

Using computational simulations, Dr. Vega and her team are trying to find the best adsorbent-refrigerant pair, and they are specifically looking for the ideal pairing with compounds known as metal-organic frameworks, or MOFs, combined with low global warming potential refrigerants including hydrofluoroolefins (HFO). They published their results in

“Several criteria can be used to select an adsorbent-refrigerant working pair,” said Dr. Vega. “The energy density that can be stored by adsorbent per unit of volume is an important indicator of performance. The difference in the adsorbed amount of refrigerant between adsorption and desorption—the working capacity—can also be considered. However, given the large number of potential materials that could be utilized, experimental evaluation is an expensive, time-consuming and tedious endeavor.”

Rather than individually test each pairing, the research team conducted simulations to guide selection of MOFs for thermal-storage applications. A total of 40 MOFs were studied using three refrigerants based on HFO, which has much lower global warming potential than the traditional hydrofluorocarbons.

The research team established a relationship between the adsorptive capacity and the properties of the materials, finding that MOFs with open metal sites interact strongly with the refrigerants, making them more suitable for thermal energy storage applications.

For cold thermal energy storage, MOFs with larger pore sizes showed a considerably higher energy density than the materials currently used commercially.

Jade Sterling
Science Writer
30 March 2021

The post Searching for Suitable Materials and Refrigerants for AC Units That Also Store Heat for Energy appeared first on Khalifa University.