Research and Innovation

Measurement of weather databases is key to any research project conceived on solar thermal/cooling research center. At present, the solar energy team of RAKRIC, in its ongoing research on solar Thermal/Cooling, is primarily dependent on weather databases that are measured on SOLAB, our outdoor research facility, as most of the research prototype experimental setups have been installed, and will be installed in the future at an outdoor facility. Most of the projects need validation with the experimental setup. Sometimes, a particular set of sensors is procured and installed for a specific project at the site. These setups are usually built near existing solar cooling/thermal centers. The weather data for the main weather station has been logged in real-time for the past seven years.

The research center has a main solar radiation weather station and multiple dedicated weather stations for different projects.

• Main Solar radiation Weather Station
• Solar cooling Weather Station
• Solar Calorimetric Weather station
• Dust Accumulation test Weather Station
  

RAK Research and Innovation Center has one of the world’s first high-precision solar tracking platforms, which can be used for concentrating solar panels. The platform floats on an air cushion and has state-of-the-art rotating systems to track the sun’s movement in the order of 10-2. This platform has been tested for the load rotation test, and it can take up to 150 tons of loads distributed over its top. This high-precision structure studies technology requiring high-precision tracking for optimum energy production. This platform has the potential to be deployed on land or offshore. Both versions are based on the principle of a torus floating on water and rotating to track the sun’s azimuth, thus ensuring optimal use of primary solar radiation received on earth. Solar radiation being concentrated can be used in solar thermal processes or photovoltaic applications.

Advantages

• Solar tracking platforms provide a unique way to supply large quantities of energy at a competitive cost.
• Limited civil engineering work is required. Materials used for the production process are mainly steel, plastic, and mirrors.
• The sun tracking is achieved by simply rotating the whole island, thus avoiding the costs of motorizing each panel.
• Concentrating solar panels used on the island are extra-flat and, therefore, not wind-sensitive.

RAK Research and Innovation Center has developed a sustainable and innovative concept to meet these demands along with the production of domestic hot. A solar thermal poly-generation (STP) system is designed and developed at SOLAB (Solar Outdoor Laboratory) to produce chilled water for air conditioning using an absorption chiller, pure water with a membrane distiller, and domestic hot water by heat recovery. The STP system has four major components: (i) Evacuated tube collector field, (ii) 10TR Absorption chiller, (iii) Air-gap membrane distillation (MD) units, (iv) Heat exchangers integrated to operate in four different modes for complete solar cooling, co-generation of pure water and domestic hot water, tri-generation of cooling, pure water and domestic hot water and co-generation of cooling and pure water. Various experiments were performed on different modes, and the analyzed results show the advantages of combined operation through effective utilization of heat lost in the process operation. In the tri-generation mode, heat could be recovered effectively from the MD process for DHW production, thus reducing overall energy consumption by MD for a kg of water production. The schematic sketch below shows the tri-generation system developed at the research center. The system could be extended further to Polygeneration for electricity production and cooling, pure water, and hot water. For more details, go through our list of publications.

Desalination is strategically vital in the MENA region as a primary source of fresh water. The UAE has become a leader in implementing alternative methods for creating fresh water resources through desalination. The majority proportion (43%) of it is consumed mainly as potable and household water. A recent survey in UAE reveals that only 6% of people drink tap water due to potential health and safety concerns over tap water. This brings in the big picture of reliance on bottled water by the urban population, and in fact, the UAE stands top as the world's largest per capita bottled water consumer. Desalination is a high energy-consuming process, and researchers worldwide strive to perfect it, making it efficient and cost-effective. But purifying the desalinated water again for bottling adds more energy along the conversion chain, and the potential environmental impact of plastic waste makes the bottling process highly unsustainable.

The need for a sustainable approach to tackle the issue of bottled water has motivated us to develop an in-house water purification unit based on Membrane Distillation (MD) technology. MD is a novel process that could be adapted effectively for many water purification applications. A difference in partial pressure serves as the driving force, and the presence of a hydrophobic membrane ensures high water quality regardless of feedstock parameters. Hot-side temperatures below 90ºC are suitable, and this process has been proven ideal for exploiting waste heat or solar thermal resources for small-scale applications.

At the RAK Research and Innovation Center, we developed an integrated system of MD into the solar hot water system that can produce 2 l/hr of distillate and fulfill the hot water demand of a single-family dwelling of five in the region. The proposed co-generation system would be ideal for maximizing the solar fraction by producing pure water in summer, thus reducing backup heating requirements. The overall thermal performance of the system could be increased and additionally acts as a source of pure distilled water. The current research study provides the design and development of a pilot test prototype for the technical evaluation of MD modules and solar thermal collectors suitable for the co-generation application.

There is an acute increase in energy utilization and production in the world in general and the UAE. This is because of the rise in population and economy. As a result of this, there is an increase in global warming and CO2 emission. To reduce the generation and mitigate its effect on the climate, one must reduce the utilization or need for energy use in society. The share of buildings in total energy consumption and its utilization is enormous, around 20%-40%, depending upon the country, and it is used in cooling, heating, hot water, home appliances, lighting, cooking, etc.

In the UAE, 40% is the building’s share of total energy consumption, of which Cooling is around 70% of the building load, Lighting is the next, and all the others will account for 20%. Thermal insulation of buildings represents an enormous potential for Energy Saving in the UAE.

A theoretical study is done at the site on different cost-effective and thermally efficient solutions related to solar insulation materials for buildings. A solar calorimeter test facility has been designed and built to perform a real outdoor test for savings obtained with solar-insulating materials. The present design is aimed to determine the heat flux reduction and the energy savings of different measures with similar indoor conditions, with and without solar insulating materials for the same ambient conditions.

The building material being tested at the calorimeter are EIFS (External insulation finishing system), PIR board retrofitting, Gypsum Rockwool wall, concrete and reflective coating.

Two types of tests are being performed at the solar calorimeter as follows:

• Steady state (same constant temperature in each calorimeter)
• Free Floating (Transient) (heat flux is directly measured through a wall)

The solar laboratory scale study shows that 20-30% energy savings can be achieved with different solar insulation materials due to heat flux reduction by 20-75%.

This study can be beneficial in building Low/Zero Energy Houses by analysis of heat flow patterns, thermal comfort, and energy performance of different insulation materials available in the market in harsh climatic conditions. Study results (real-time) can be used to select materials best for the market and the environment.

The center specializes in testing all PV panels under diverse weather conditions to design high-yield systems. Our advanced testing capabilities, including energy yield and IV curve analysis, guide us in selecting the best technologies, optimizing system design, and assessing real-time performance through simulations. Equipped with state-of-the-art software and hardware, we ensure accurate and reliable testing for optimal photovoltaic solutions.

Absorption chilling is a thermal energy technology that provides building air conditioning. In recent years, it has gained much attention due to its uniqueness in utilizing solar thermal energy and low-grade waste heat liberated by industries.

RAKRIC has been focusing on research activities in solar cooling for the past five years. The research facility has successfully installed two absorption chillers and analyzed their performance. The facility has a 3.5kW Rotatica absorption chiller and 35 kW Yazaksingle-stage absorption chiller pilot plants with a rated COP of 0.5 and 0.7, respectively. An evacuated tube collector field drives the absorption chiller plants with a gross area of 130 m2. The system is fully operational to provide air conditioning to office cabins.

Several research works were conducted rigorously and documented in the form of master student theses, research internships, conference proceedings, and journal publications. The solar cooling facility has assisted in completing five master theses and four research internships for master students from Sweden, Switzerland, and Germany. We have also presented our research works at international conference platforms, in Solar Heating and Cooling Conference held in Germany, Eurosun held in France, the Renewable energy congress held in London, etc.

In terms of technology, three different types of absorption chillers are available. The selection is based on operating temperatures, COP, area availability, etc. Several renowned manufacturers are available in Japan, the UK, India, and the USA. Selection of the absorption chillers is further based on the type of working fluid, placement, application, and economics.

Concentrated Solar Power using Extra Flat Collector

Among various Solar Energy conversion technologies available today, Extra flat Concentrators stand out because of their simplicity, scalability, and low cost.

The main idea is to use an array of inexpensive mirror blades and position them so that the maximum amount of sun rays can be concentrated on the solar thermal absorber tube (figure 1 suggests the orientation). Using ordinary mirrors makes the blades' maintenance easy and less expensive. Being flat compared to other techniques, it gives less resistance to wind, which is very much needed for scalable design implementation.