Solar Refrigeration System Research Articles

Simulation of the performance of continuous solar-powered adsorption refrigeration system for optimal use in Zaria, Nigeria

Cooling without electricity is the reason for solar adorption refrigeration systems. The epileptic power supply, especially in developing countries, makes solar refrigeration a very attractive option. This is coupled with the abundance of solar energy, making it a favourable alternative power source amongst other power mixes. This article introduces a solar adsorption refrigerator that continually generates cooling using solar energy as a standalone. Thus, this study aims to simulate and analyse the feasibility of refrigeration from a system that uses a blend of zeolite-based adsorbents and water (H2O) as adsorbate pairs via four solar concentrating collectors, two for adsorption and two for desorption using TRNSYS 16.0 simulation software. Unlike the conventional refrigeration system, the compressor was replaced with a solar concentrating collector while other components, such as the condenser, evaporator, and throttling valves, remained. The findings demonstrate that the technology delivered continuous cooling, and due to the comparatively intense beam radiation during the middle of the day, the cooling rate increased.

Performance evaluation of external compound parabolic concentrator integrated with thermal storage tank for domestic solar refrigeration system.

The aim of this research was to develop a model for a solar refrigeration system (SRS) that utilizes an External Compound Parabolic Collector and a thermal energy storage system (TESS) for solar water heating in Chennai, India. The system parameters were optimized using TRNSYS software by varying factors such as collector area, mass flow rate of heat transfer fluid, and storage system volume and height. The resulting optimized system was found to meet 80% of hot water requirements for the application on an annual basis, with an annual collector energy efficiency of 58% and an annual TESS exergy efficiency of 64% for a discharge period of 6h per day. In addition, the thermal performance of 3.5kW SRS was studied by connecting it to an optimized solar water heating system (SWHS). The system was found to generate an average cooling energy of 12.26MJ/h annually, with a coefficient of performance of 0.59. By demonstrating the ability to efficiently generate both hot water and cooling energy, the results of this study indicate the potential for utilizing a SWHS in combination with STST and SRS. The optimization of system parameters and the use of exergy analysis provide valuable insights into the thermal behavior and performance of the system, which can inform future designs and improve the overall efficiency of similar systems.

Analytical modelling of food storage cooling with solar ammonia-water absorption system, powered by parabolic trough collectors. Method

The study presents a new analytical model capable to reveal the thermal behaviour of all the components of the solar ammonia-water absorption system, powered by parabolic trough collectors, serving different types of food storages: refrigeration chamber, refrigerated food storage, freezing chamber and frozen food storage. The heat inputs, that determine the total cooling load, for each food storage spaces consist of: heat gains through walls, heat gains through ventilation (fresh air), heat that must be dissipated from the stored products (technological cooling load required to cool down the products) and heat gains through operation. The influence of the number of solar parabolic trough collectors and of the storage tank size on different parameters of the refrigeration plant are investigated under low and high storage temperatures.•Food cooling with solar absorption refrigeration system.•Hourly based variation of NH3-H2O solar absorption system performances.•Long term simulation of solar absorption cooling for refrigeration and cooling.

Mathematical modeling and performance analysis of a solar assisted vapour absorption refrigeration system

Climate change is the hottest topic today on earth. Traditional HVAC’s harm the environment and stand out to be a major contributor to global warming. One of the many techniques to mitigate the current climate crisis is by utilizing the abundantly available solar radiation. Solar evacuated tube collectors are used to absorb solar radiation. This solar power is used to provide solar cooling technologies. Unlike the conventional HVAC’s thermally driven absorption cooling is a boon in today’s era. In the following research work, the study aims to provide numerical modeling of a solar assisted air-conditioning unit through the first law of thermodynamics using mass balancing equations for the province of Delhi in July. This research work’s aim is to build and evaluate a Li-Br absorption cooler with a capacity of 1 KW. This paper aims to provide characteristic design features of components and measures the efficiency of the system at operating conditions. PCM based thermal energy storage tank is adopted which helps to supply cold air even at no sunlight hours. As a result of this research study, such solar assisted air conditioners turn out to be a chosen solution for sustainability.

Thermodynamic analysis of a solar refrigeration system based on combined supercritical CO<SUB align="right">2 power and cascaded refrigeration cycle

Thermodynamic analysis of a solar refrigeration system based on combined supercritical CO<SUB align="right">2 power and cascaded refrigeration cycle

Thermodynamic analysis of a solar refrigeration system based on combined supercritical CO<SUB align="right">2 power and cascaded refrigeration cycle

This communication proposed a solar driven system based on supercritical CO2 (sCO2) power cycle integrated with cascaded refrigeration cycle (CRC) to refrigerate a thermal load of below than -40°C. The impact of varying solar irradiance (DNI), type of solar heat transfer fluid (SHTF), and the working fluid of CRC on refrigeration capacity and exergy efficiency of combined system are investigated. Results indicate helium as the most efficient SHTF with air to follow. It is shown that maximum refrigeration is produced when operating with helium as SHTF and propylene as the refrigerant for CRC. From exergetic point of view, propylene provides higher exergy efficiency; CO2 is the one with lower, while N2O presents intermediate results. The exergy efficiency of the system for the propylene, N2O and CO2 is determined as 9.64%, 8.73%, and 8.47%, respectively.

Performance assessment of a perovskite solar cell-driven thermionic refrigerator hybrid system

To develop a high-performance solar refrigeration technology, a novel refrigeration system composed of a perovskite solar cell (PSC) and a thermionic refrigerator (TIR) is constructed. Based on theories of photovoltaic effect, thermionic emission and non-equilibrium thermodynamics, the coefficient of performance (COP) and refrigerating capacity of the integrated system are mathematically expressed, in which the various irreversible losses are taken into consideration. The integration characteristics and coupling relationships between the PSC and TIR are investigated, and the working voltage regions for the combined operation of the subsystems are determined. Furthermore, the impacts of the area ratio, the work function, the environment temperature, the cold reservoir temperature and the heat transfer coefficient on systemic performance are evaluated in detail. Numerical calculation examples illustrate that the maximum COP and maximum refrigerating capacity of the integrated system are 0.81 and 81.2 W, respectively. Analysis results show that there exist optimal area ratio and work function to optimize the system performance. The present study may offer some fresh perspectives on the evolution of the solar refrigeration system.

Exergoeconomic Analysis of a Variable Area Solar Ejector Refrigeration System under Hot Climatic Conditions

The present study investigates low-grade heat utilization in ejector refrigeration systems under hot climatic conditions. A variable area ejector is used to maximize the harvested heat from the generator of the solar system at peak times. Exergy, economic, and exergoeconomic analyses are conducted to evaluate the performance of the system. A thermodynamic model of the system has been developed using Ebsilon Professional software. Available experimental and theoretical data validate the results. The effects of properties of the working fluids, ejector geometry, and operation conditions are also evaluated. It was found that the coefficient of performance of the system reached 0.45 at a generator pressure of 3 bars. Furthermore, it was noticed that the overall exergy efficiency could be increased for a fixed generator temperature while increasing the ejector area ratio. A value of 21% exergetic efficiency was calculated for the system. The exergoeconomic analysis of the system demonstrated that heat exchangers are required to be improved thermodynamically at the expense of the capital investment cost.

Solar-Powered Refrigeration Systems for Kenya Sub-Counties Health facilities for COVID-19 Vaccines Storage; Opportunities, Challenges, and Future Prospects

The economic prosperity plus technological growth of each & every county depend heavily on energy security, and the energy availability portrays the quality of life in that country. Solar energy is an alternative energy source for cooling systems where power is costly, unreliable, and unsustainable—the main options for electrically-powered refrigeration systems available for several years; are our gas and kerosene-driven refrigerators. The solar refrigeration system was a promising advancement in the early 1980s, creating an alternative to absorption technology to cater to the cold chain requirements in off-grid areas. The main objective of this research is to determine the feasibility of solar-powered refrigeration systems for rural dispensaries, sub-counties health centers, and health posts in Kenya; this is in line with the current COVID-19 pandemic, which demands that the vaccine be supplied to the local populace. This article provides essential recommendations on the solar-powered refrigeration system and highlights some critical parameters for the successful implementation of solar-powered refrigeration units into vaccination programs in the future, including; The supply chain of the vaccines in the country, the current state of the health system at sub-county hospitals, areas of improvements, and the recommendations

Experimental study on performance of phase change microcapsule cold storage solar composite refrigeration system

This paper proposes a solar jet-compression composite cooling system with phase change microcapsule storage and build a cooling storage-type solar composite refrigeration system and operational performance test platform. A microencapsulated suspension with a base solution of deionized water was prepared, and sodium dodecyl sulfate (SDS) 0.2%, xanthan gum 0.2%, and sodium chloride (NaCl) 0.5% were added. The operating characteristics of the solar cooling system and the variation in the storage performance of the phase change material under evaporation temperatures of −5 °C and −10 °C and suspension mass fractions of 10% and 15% were investigated. It was found that the temperature of the suspension with a 15% mass fraction decreased by 7.34 °C when the storage time reached 100 min and that of the suspension with a 10% mass fraction decreased by 8.20 °C in the same storage time. The storage capacity of the microencapsulated suspension was greater than that of water within the same storage time. The storage capacity of the 10% suspension at 33 min is 2765.01 kJ, which is 63.1% more than that of water, indicating that the suspension has better storage performance.

Optimization of A Solar Ejector Refrigeration System in the Region of Adrar, Algeria

This study aims to simulate a solar ejector refrigeration system in the region of Adrar (27.82 N, 0.18 W). It is the first investigation of such refrigeration system in this region, the importance of this study is to benefit from the free intense solar energy for cooling and air conditioning and reduce using electrical energy produced by thermal power station which is harmful to the environment and causing warming global. It is a theoretical study using real gas equation (REFPROP database). The system is inspected for various evaporator temperatures from 0 to 30 °C and for various condenser temperatures from 25 to 50 °C. For each situation, the system is optimized by choosing the best ejector parameters and the ideal generator temperature. Different refrigerants are used as R11, R134a and R717 (ammonia). The last one is observed to be the best fluid in all the working conditions. More explicitly, the highest COPs is 0.28 when the system produces refrigeration at 30 °C and the boiler temperature is 90 °C. The COPs values are acceptable and very interesting, and it’s higher than other cities in the world like Athens, this study can be generalized in other hot regions. The examination is performed with a code written in Fortran.
 HIGHLIGHTS
 
 The importance of this study is to benefit from the free intense solar energy for cooling and air conditioning and reduce using electrical energy
 For each situation, the system is optimized by choosing the best ejector parameters and the ideal generator temperature. Different refrigerants are used as R11, R134a and R717 (ammonia). The last one is observed to be the best fluid in all the working conditions
 More explicitly, the highest COPs is 0.28 when the system produces refrigeration at 30 °C and the boiler temperature is 90 °C
 This study can be generalized in other hot regions
 
 GRAPHICAL ABSTRACT

Experimental study on the operating characteristics of refrigerant pumps for solar ejector refrigeration systems

A bench performance test for a refrigerant pump was built to analyze the variations among parameters such as flow rate, head, rotational speed, efficiency/total efficiency and power consumption of a multistage centrifugal pump under different working conditions. The study showed that the outlet pressure, differential pressure and power consumption of the pump increased with increasing frequencies at the rated flow rate of 1 m3/h and inlet pressure pc = 0.454 MPa. The total pump efficiency showed a trend toward first increasing and then decreasing, and the maximum value was approximately 27.7%. When the refrigerant pump was at a frequency of 37.5 Hz and the inlet pressure was between 0.338 and 0.523 MPa, the pump outlet pressure and differential pressure decreased with increasing flow rates, and the pump outlet pressure increased with increasing inlet pressures. While the pump differential pressure increased with the increase in suction pressure, the pump power consumption increased with the increase in flow and increased slowly with the pump inlet pressure. With the increase in the flow rate, the total efficiency of the pump showed a tendency toward first increasing and then slowly declining. The total efficiency of the pump was between 4.0% and 30.2% at flow rates between 0 and 1.8 m3/h. Under the same conditions, when the pump operated under low flow rate and high pressure differential conditions, and the refrigerant pump efficiency was low.

A new variable mixing chamber ejector: CFD assessment

• A new variable mixing chamber ejector is proposed for waste-heat driven chillers. • The mixing chamber cross-sectional area can be increased or reduced. • The cooling capacity increased by up to 120%. • The backflow condensing temperature increased by almost 8 °C. Research on the reduction of refrigeration systems energy consumption is a topic in which popularity benefits from the contextual growth of the refrigeration market. Solar or waste heat-driven ejector refrigeration systems are very promising in this context. However, the lack of operational flexibility of ejectors penalizes the performance of such systems. Since the mixing chamber has a fixed cross-section, for condensation temperatures above critical, the cooling capacity vanishes and, for temperatures lower than critical, the cooling capacity stagnates. The paper proposes a new variable mixing chamber solution that overcomes these limitations. It is a range extender that allows ejectors to operate at high cooling capacity all over the operation range of the system. This range extender is based on the concept of lateral cylindrical moving slots. The paper compares the new ejector to a reference ejector from the literature. First, the Computational Fluid Mechanics (CFD) model viability is evaluated thanks to the experimental measurements on the reference ejector. Then, the new system’s performance is evaluated. The results show that the adaptation of the mixing chamber section to the condensation temperature allows increasing the cooling capacity without supplementary motive energy. That leads to an increase of up to 120% of the cooling capacity at low condensation temperatures and a shifting of 8 °C of the critical temperature. Such extension of the operational range was never obtained before. That means that an ejector stalling at 33 °C could operate at 41 °C using the proposed range extender.

Simulation of an improved solar absorption refrigeration system with phase change materials

Aiming at the problems of low solar energy utilization rate, poor intermittent, low stability and poor energy saving effect in traditional solar absorption refrigeration system, a lithium bromide-water absorption refrigeration system driven by solar in Tai’an was taken as the research object. An improved solar absorption refrigeration system with phase change was presented. In typical day and whole refrigeration period, the traditional solar absorption refrigeration system with and without phase change were simulated by TRNSYS transient simulation software. Their collector efficiency, unit cooling capacity and COP were comparatively analyzed. The results showed that the collector efficiency of the improved solar absorption refrigeration system with phase change was 4.2% higher than that of the traditional solar absorption refrigeration system without phase change. The unit cooling capacity was 2.8% lower than that of the traditional system, which store the excess cooling capacity with the help of PCMs. The average COP of traditional absorption system and improved solar absorption refrigeration system were 0.737 and 0.679, respectively. This manuscript provides a theoretical basis for the development of solar phase change heat storage absorption refrigeration system.

Implementation of Solar Heat Energy and Adsorption Cooling Mechanism for Milk Pasteurization Application

The use of renewable energy is crucial to the global growth of sustainability. Milk business amongst many other food industry divisions requires a significant amount of energy, making the meal processing business one of the most energy-intensive industries. As of right now, more than 30 percent of the dairy produced in India is processed. In distant parts of India, milk spoiling is more common due to the delay among milking and storing; as a result, facilities for quick pasteurization and storage are needed. Heated is necessary for pasteurization. Since for a long time, the Indian milk industry has relied on nonrenewable energy sources, that are not only becoming much more costly but are also to blame for significant environmental issues including greenhouse gases and health issues. Consequently, scientific communities, environmental and social organizations, and the governments have all pushed the use of green energy. Solar energy has been shown to be the most viable among various sustainable and renewable energies given the geographical position of India. Solar energy can be used to pasteurize milk because of the energy intensity and range of temperature requirements. Adsorbent refrigerator is recommended here since it is powered by waste/solar heat and can store (200 liters of milk) at low temperatures until it is distributed after the pasteurization process (easily available from farm waste). The solar collector of evacuated tube is used for minimizing heat loss and pasteurizing milk. The outcome demonstrates that milk can be simply pasteurized at 73°C for 25minutes at a flow rate of 5 liter per minutes. A solar energy adsorbent refrigeration system has been constructed and described for keeping 200 liters of milk at 10-15°C for 9–11 hours. Investigation findings indicate that the specific cooling power of the system is sufficient to store 200 liters of milk at 5.8 kW/kg and 5.5 kW/kg for 500 liter per hours hot water supplied at 92°C, 32°C condenser temperatures, and 5°C evaporator temperatures. The heat loss of evacuated tube collector is compared to solar concentrator. The study results provide evacuated tube collector is better for pasteurizing milk since to its highly efficient, longevity, and compactness.

Numerical Investigation of an Fe3O4 Nanofluid Filled in an Obround Enclosure Heated by Solar Energy

This research work deals with a technological application of a 2D numerical solar Magneto-Hydro-Dynamic (MHD) investigation of an Fe3O4-Water nanofluid, filled in an obround-shaped enclosure. The cold temperature is imposed on a symmetric arc wall located at the semicircular side of the enclosure, while the hot temperature is related to a circular rotating heat source located in the middle of the enclosure. The remaining walls of the enclosure are supposed to be insulated. The cold wall is considered chilled using a solar refrigeration system. The heat source is considered as a blackbody receiving solar radiation. The mathematical problem, stating the governing equations of the considered MHD problem (continuity equation, Navier Stokes equations and energy conservation equation), is elaborated in its dimension and dimensionless form. The dimensionless form permits to generalize dimensionally the considered problem. The considered problem Numerical results, stating the influences of geometrical, magnetic and Fe3O4-Water nanofluid operating parameters on the flow (streamlines and velocity magnitudes) and thermal behaviors of the Fe3O4-Water nanofluid (temperature contours) are presented, discussed and interpreted. The geometrical parameters are the wall arc angle, the heat source velocity, and the radius. The magnetic parameters are the Hartmann number and the magnetic field inclination angle. The Fe3O4-Water nanofluid operating parameters are principally the Rayleigh number.

Performance modelling of an electric vapor compression solar refrigeration system (SE-VCR) case for Madagascar

This study presents an evaluation of the performance of an electric vapor compression solar refrigeration system coupled with solar energies for the different climatic zones in Madagascar. For the 5 selected cities, a building of the same constructive design was used. Hourly building heat loads were estimated from the heat balance method using meteorological data from selected cities such as hourly average solar radiation and atmospheric temperatures. Then, the hourly evaluation of various parameters such as the coefficient of performance, the capacity of the condenser, the electrical consumption of the compressor and the power of the photovoltaic generators as well as its surface for different evaporation temperatures were determined. It was determined that the SE-VCR system could be used successfully for the province of Mahajanga, Antsiranana, Toliara and Tamatave while for the city of Antananarivo was not very interesting.For these 4 cities, the coefficient of performance varies from around 3.3 to 4.43 for an evaporation temperature Te = 0 ° C. And the power of the compressor varies from 5.66 to 7.5 kW with a peak power of the solar panels varying from 21.16 to 25.23 kWp with a respective surface of 104.93 to 125.12 m². The overall efficiency of the installation varies from 0.483 to 0.521.

Influence of disturbances in the operating conditions on the refrigeration performance of a regenerative solar absorption refrigeration system with a biomass assisted combustion device

To reduce the fluctuation of the heat source water temperature and ambient temperature caused by variations in solar radiation, a solar absorption refrigeration system with a supplementary biomass combustion device for the office area of a factory was designed. A numerical model of the solar energy absorption refrigeration system based on the Aspen Plus software was developed. In particular, the effects of the heat source water temperature, condenser temperature, evaporation temperature, and dilute solution flow rate on the cooling capacity, coefficient of performance, unit equipment duty, and generator temperature during actual operation were investigated. The heat load of each piece of equipment in the unit were found to increase correspondingly with the increase of the heat source temperature when the evaporating temperature and condensing temperature are constant. The coefficient of performance of the unit decreased as the condensing temperature increased keeping the temperature of the heat source constant. The results demonstrated that the flow rate of the dilute solution has effects on the occurrence temperature, cooling capacity, and the unit performance coefficient.

Analysis of Energy Consumption of the Lyophilizer System Using Solar Absorption Refrigeration

To design a lyophilizer plant in Guangzhou, the author of this paper used a solar energy absorption refrigeration system and a waste heat of solar absorption refrigeration system. Using Trnsys software, the simulation results show that the solar assurance rate of 74.96% on July 28th can save coal quantity of about 236.8 kg, a solar assurance rate of 53.48% in July can save coal quantity of about 4790.9 kg, and an annual solar assurance rate of 39.06% can save about 40657.1 kg, and each have good environmental benefits.

Research on Solar Adsorption Refrigeration System

In order to achieve solar adsorption refrigeration, this paper studies the surface water source solar absorption refrigeration system combined with surface water source cooling and solar absorbent refrigeration techniques: the solar radiation intensity is adjusted by changing the distance between iodine tungsten lamps and solar cold tubes. The results show that the entire cycle has a range of solar radiation intensity of 400 to 1000 W/m2, and the indoor ambient temperature ranges from 19 to 25∘C, and the humidity is maintained around 40%. The highest temperature in the solar cold tube adsorption bed is 12∘C; during the adsorption process, the temperature drops to about 20∘C; the solar cold tube is 160 kJ in one cycle of the solar cold tube, and the cooling coefficient is about 0.15. Conclusion: solar cold tubes can effectively utilize solar refrigeration, it is a refrigeration method for environmentally friendly, no greenhouse effects and ozone destruction, which has potential application value and has energy saving and environmental protection.