Efficient Energy Source Research Articles

Demand flexibility and its impact on a PEM fuel cell-based integrated energy supply system with humidity control

The development of efficient energy systems and renewable alternative energy sources has attracted substantial attention owing to the rise in environmental deterioration and energy usage. A combined cooling, heating, and power (CCHP) system can fully use different types of energy with low emissions and offers a viable solution to address these issues. Demand flexibility is a key issue in collaborating with different types of supplies and demands for optimal system operation. In this study, a proton-exchange membrane fuel cell driven CCHP system with humidity control is proposed to fully investigate the impact of demand flexibility on system operation. A novel flexible load regulation strategy was designed for the proposed system. The results show that flexible load regulation can reduce the thermal storage capacity by 25 %. Supplement heating and cooling do not need operate in winter and summer. With flexible regulation, the heating load can be reduced by 15.69 % in winter, and the cooling and dehumidification loads can be reduced by 30.71 % and 6.09 % in summer. The reductions in hydrogen consumption can reach 1.98 % and 7.51 % during winter and summer. The proposed method can simultaneously increase the exergy efficiency and reduce carbon emission, as well as the economy cost.

Harvesting energy vibration derived from the rotational speed of a A 4-stroke engine

The utilization of vibration energy from a 4-stroke engine as a potential source of electrical energy. Previous studies have focused on analyzing the vibration characteristics and frequency response functions of the 4-stroke engine, but there is a lack of research on harnessing vibration energy as a source of electrical energy. Therefore, this research aims to fill this gap by developing a system to harness the vibration energy from the 4-stroke engine, making it a primary focus of the study. The method employed is an experimental study involving data collection using an FFT Analyzer and Matlab. The research results indicate the presence of several mode shapes in the 4-stroke piston motor. The energy harvesting device utilized is of the electromagnetic type. However, the research reveals that the utilization of vibrations from the 4-stroke piston motor as a source of electrical energy is still not efficient and requires further development. There are various mode shapes in the 4-stroke piston motor at different rotational speeds, but the electromagnetic energy harvesting device used is unable to generate significant electrical energy. Therefore, this research provides a foundation for conducting further research in utilizing the vibrations of a 4-stroke piston motor as a more efficient source of electrical energy

Oxidative Stress in Military Missions-Impact and Management Strategies: A Narrative Analysis.

This narrative review comprehensively examines the impact of oxidative stress on military personnel, highlighting the crucial role of physical exercise and tailored diets, particularly the ketogenic diet, in minimizing this stress. Through a meticulous analysis of the recent literature, the study emphasizes how regular physical exercise not only enhances cardiovascular, cognitive, and musculoskeletal health but is also essential in neutralizing the effects of oxidative stress, thereby improving endurance and performance during long-term missions. Furthermore, the implementation of the ketogenic diet provides an efficient and consistent energy source through ketone bodies, tailored to the specific energy requirements of military activities, and significantly contributes to the reduction in reactive oxygen species production, thus protecting against cellular deterioration under extreme stress. The study also underlines the importance of integrating advanced technologies, such as wearable devices and smart sensors that allow for the precise and real-time monitoring of oxidative stress and physiological responses, thus facilitating the customization of training and nutritional regimes. Observations from this review emphasize significant variability among individuals in responses to oxidative stress, highlighting the need for a personalized approach in formulating intervention strategies. It is crucial to develop and implement well-monitored, personalized supplementation protocols to ensure that each member of the military personnel receives a regimen tailored to their specific needs, thereby maximizing the effectiveness of measures to combat oxidative stress. This analysis makes a valuable contribution to the specialized literature, proposing a detailed framework for addressing oxidative stress in the armed forces and opening new directions for future research with the aim of optimizing clinical practices and improving the health and performance of military personnel under stress and specific challenges of the military field.

RESEARCH OF STRUCTURAL AND MECHANICAL PROPERTIES OF MEAT AS AN OBJECT OF PROCESSING IN MEAT COMMINUTOR

Reliable assessments of the state of modern energy show the relevance of scientific and technical developments aimed at solving its problems. In this regard, the use of resonance phenomena in electrical circuits with active-reactive elements acquires particular significance. Their various combinations open up exceptional opportunities for creating fundamentally new efficient energy sources. This article discusses a resonant active electrical power amplifier containing a sequence of several electrically connected active-reactive circuits, which, depending on the purpose, are excited in the voltage resonance or current resonance mode. An equivalent circuit is proposed for the proposed resonant amplifier of active electrical power, represented by two blocks, each of which consists of a sequence of inductively coupled active-reactive circuits excited at the same frequency. Calculations are presented showing the theoretical justification for the performance of the proposed scheme. The analysis of ongoing electromagnetic processes was carried out using well-known methods of the theory of electrical circuits without involving any hypotheses about the physics of resonance phenomena. It is shown that in the proposed amplifier circuit, the first block amplifies the reactive power of the harmonic signal with a high conversion coefficient, the second, with a slight gain, converts the reactive power of the harmonic signal into active power. The results of calculations are presented, illustrating the functional dependence of the integral gain on the main characteristics of the output resonant circuit. Numerical estimates of the main characteristics of the proposed circuit showed that with an appropriate choice of its parameters, high values of the output characteristics are possible, so the gain can reach a value of ~ 48. The significance of the results obtained for practice lies in their use for formulating recommendations for the creation of real efficient sources of electrical energy, the principle whose actions are based on the use of natural resonance phenomena.

Application of tiered human health and environmental risk assessment to develop safe and sustainable by design perovskite-based devices

Metal halide perovskite materials have gained significant attention in recent years due to their potential energy and lighting applications. They are potentially vital materials for the current energy transition which aims to minimize the dependence on fossil fuels and limited land resources by the increased use of cost-effective and efficient renewable energy sources. The European Green Deal policy, which sets out its ambitions in the Chemicals Strategy for Sustainability, can help its transition to a Safe and Sustainable by Design (SSbD) development. In this context, we applied the SSbD approach to selected perovskite-based devices which are still in their development state, by assessing potential human health and environmental risks along their life cycle. We applied the SSbD approach in a tiered manner so that it aligns with successive Technology Readiness Levels (TRL) to help the innovators ensuring safety and sustainability aspects throughout the various stages of their product development. Thus, the SSbD assessment began right from the start of the development (TRL 1–2), when there can be (huge) gaps and uncertainty in the product knowledge, up to the later stages of higher TRL when the product knowledge is more abundant and certain. In our assessment, we mainly focused on the human health risk of the perovskite-based devices and considered the implications of environmental emissions of hazardous substances on the human health. We further bring attention to the alternatives which could help mitigate concerns over their safety and sustainability for a responsible technology development and deployment. Results of this study are important to understand the detailed sustainability assessment in which we look at multiple sustainability aspects and its potential future impacts due to technology scale-up in the future.

Hydrogen generation from methanolysis of sodium borohydride using boric acid as a catalyst

ABSTRACT Hydrogen plays a critical role in reducing dependence on fossil fuels and combating climate change as a clean, highly efficient, and renewable energy source. In this study, hydrogen production via methanolysis of sodium borohydride (NaBH4) has been investigated in the presence of boric acid (H3BO3) catalyst. The effect of various parameters on hydrogen generation rate has been reported and the effect of temperature, H3BO3 catalyst concentration, methanol volume and NaBH4 concentration has been studied in the range of 20–50°C, 0.539–2.695 mM, 2–20 mL, and 0.176–0.881 mM, respectively. The kinetic parameters are estimated with the power law model and the reaction order and activation energy are found as 2 and 33.25 kJ·mol−1, respectively. The highest hydrogen generation rate (HGR) is achieved as 628,117 mL·min−1·g cat−1 at 50°C with 1.078 mM H3BO3 and 0.352 M NaBH4 concentrations and 15 mL methanol volume. This study’s notable result is the emphasis on the effect of using a very small amount of boric acid. Because the use of a high amount of boric acid as a catalyst causes steric hindrance in the methanolysis reaction of trimethyl borate, which is the product of the equilibrium reaction between boric acid and excess alcohol in the solution. This situation has been avoided by using a lower amount of boric acid. Thus, it demonstrates that environmentally friendly, efficient, and cost-effective boric acid has great potential in hydrogen production via methanolysis and that its performance can be further improved with more work on the optimization of catalyst concentration.

Assessment of Triboelectric Nanogenerators for Electric Field Energy Harvesting.

Electric-field energy harvesters (EFEHs) have emerged as a promising technology for harnessing the electric field surrounding energized environments. Current research indicates that EFEHs are closely associated with Tribo-Electric Nano-Generators (TENGs). However, the performance of TENGs in energized environments remains unclear. This work aims to evaluate the performance of TENGs in electric-field energy harvesting applications. For this purpose, TENGs of different sizes, operating in single-electrode mode were conceptualized, assembled, and experimentally tested. Each TENG was mounted on a 1.5 HP single-phase induction motor, operating at nominal parameters of 8 A, 230 V, and 50 Hz. In addition, the contact layer was mounted on a linear motor to control kinematic stimuli. The TENGs successfully induced electric fields and provided satisfactory performance to collect electrostatic charges in fairly variable electric fields. Experimental findings disclosed an approximate increase in energy collection ranging from 1.51% to 10.49% when utilizing TENGs compared to simple EFEHs. The observed correlation between power density and electric field highlights TENGs as a more efficient energy source in electrified environments compared to EFEHs, thereby contributing to the ongoing research objectives of the authors.

Hydrophobic and Luminescent Polydimethylsiloxane PDMS-Y2O3:Eu3+ Coating for Power Enhancement and UV Protection of Si Solar Cells.

Solar cells have been developed as a highly efficient source of alternative energy, collecting photons from sunlight and turning them into electricity. On the other hand, ultraviolet (UV) radiation has a substantial impact on solar cells by damaging their active layers and, as a result, lowering their efficiency. Potential solutions include the blocking of UV light (which can reduce the power output of solar cells) or converting UV photons into visible light using down-conversion optical materials. In this work, we propose a novel hydrophobic coating based on a polydimethylsiloxane (PDMS) layer with embedded red emitting Y2O3:Eu3+ (quantum yield = 78.3%) particles for UV radiation screening and conversion purposes. The favorable features of the PDMS-Y2O3:Eu3+ coating were examined using commercially available polycrystalline silicon solar cells, resulting in a notable increase in the power conversion efficiency (PCE) by ~9.23%. The chemical and UV stability of the developed coatings were assessed by exposing them to various chemical conditions and UV irradiation. It was found that the developed coating can endure tough environmental conditions, making it potentially useful as a UV-protective, water-repellent, and efficiency-enhancing coating for solar cells.

Super-Resolution for Land Surface Temperature Retrieval Images via Cross-Scale Diffusion Model Using Reference Images

Geothermal resources are efficient, clean, and renewable energy sources. Using high-resolution images captured by remote sensing satellites for temperature retrieval and searching for geothermal anomaly areas is an efficient method. However, obtaining land surface temperature retrieval images requires multiple steps of calculation, which can result in a great loss of image information and resolution. Therefore, the super-resolution reconstruction of LST retrieval images is currently a challenge in geothermal resource exploration. Although the current super-resolution methods for LST retrieval images can appropriately restore image quality, the overall restoration of the surface temperature information in the region is still not ideal. We propose a cross-scale reference image super-resolution model based on a diffusion model using deep learning technology. First, we propose the Pre-Super-Resolution Network (PreNet), which can improve both indices and the visual effect of images. Second, to reduce the white noise in the super-resolution images, we propose the Cross-Scale Reference Image Attention Mechanism (CSRIAM). The introduction of this mechanism greatly reduces noise in the images and improves the overall image quality. Compared to previous methods, we improved both experimental indices such as Peak Signal-to-Noise Ratio (PSNR), Structural Similarity (SSIM), etc., and vision quality, and optimized the recovery of geothermal anomalies. Through our experimental results, we found that the CS-Diffusion model has a very strong ability to restore the image quality of the LST retrieval. After restoring its image quality, we can make a positive contribution to subsequent geothermal resource exploration.

Study of the influence of different ignition times on detonation generation and shock wave propagation in high-pressure hydrogen leakage

Hydrogen is an efficient, clean, and renewable energy source. When determining a place for hydrogen energy storage and injection into vehicles, the main safety concern of hydrogen refueling stations is high-pressure hydrogen leakage. In this paper, the CFD method is used to study the effect of different ignition times on the explosion and shock wave propagation of high-pressure hydrogen gas leakage, analyze the distribution of flammable gas clouds, and evaluate the impact of combustion flames, temperature, and explosion-induced overpressure on refueling stations. The results show that the concentration of gas clouds ranges from 0 to 80% (volume concentration). Explosion and combustion phenomena occur at different ignition times during the high-pressure hydrogen gas leakage stage, with a maximum pressure of 2.6 bar and a high temperature of 1500–2400 K. After a high-pressure hydrogen leak, ignition can occur only as an explosive phenomenon. This generates a pressure of up to 3.1 bar and a short-lived high temperature. The pressure increases with the length of the leak, and the hazardous area varies depending on the time of ignition. This paper provides theoretical support for safety issues related to high-pressure hydrogen leakage in refueling stations.

Comparative study of interfacial charge transfer at the junction between CuInS2:In2S3/g-C3N4 photocatalysts for sacrificial hydrogen evolution activity

The quest for sustainable and efficient renewable energy sources has escalated in recent years, with photocatalytic hydrogen production gaining prominence due to its potential to harness solar energy for clean fuel generation. In this study, we design 2D/2D heterostructure CuInS2:In2S3/g-C3N4 nanosheets utilizing electrostatic interaction for hydrogen evolution reaction under visible light irradiation. Integrating CuInS2:In2S3 and g-C3N4 layers to form an interfacial 2D:2D heterostructure results in a broad light absorption range, effective charge separation, and excellent stability. The heterostructure ensures efficient interfacial charge transfer pathways, mitigating electron-hole recombination and promoting hydrogen evolution. The hybrid nanosheets prepared with the hydrothermal method exhibited ∼40-fold synergistic enhancement in hydrogen production and long-term stability. The synergistic boost in activity resulted from the formation of S-scheme heterojunctions (CuInS2/g-C3N4 and CuInS2/In2S3) within hybrid nanosheets.

Towards carbon-free mobility: The feasibility of hydrogen and ammonia as zero carbon fuels in spark ignition light-duty vehicles

Global warming is a major environmental issue caused by the release of greenhouse gases, such as carbon dioxide into the atmosphere. Light-duty vehicles (LDVs) including passenger cars and light-duty trucks, are a significant contributor to greenhouse gas emissions. The transportation sector is responsible for approximately 23% of global CO2 emissions, with LDVs accounting for a substantial portion of these emissions. This paper aims to investigate the feasibility of zero-carbon fuels with focus on hydrogen and ammonia in spark ignition internal combustion engines for light-duty vehicles. With the increasing demand for sustainable and carbon-free mobility, alternative fuels such as hydrogen and ammonia are gaining attention as potential solutions. The properties and characteristics of these fuels and their potential for utilising them as a fuel in internal combustion engines are also reviewed. Current challenges and opportunities associated with the use of these fuels, including production, storage, and distribution, will be discussed. While there are still technical and infrastructural challenges that need to be addressed, hydrogen and ammonia have the potential to provide clean and efficient energy sources for light-duty vehicles. The development of these fuels, along with advancements in internal combustion engine technology, can help pave the way towards a carbon-free future for mobility.

Supramolecular confinement effect enabling light-harvesting system for photocatalytic α-oxyamination reaction

The supramolecular Förster resonance energy transfer (FRET) is seen as a promising approach for organic photocatalysis using dyes as catalysts, because it combines the high efficiency of energy transfer with the dynamic responsiveness based on non-covalent interactions. Here we propose a supramolecular FRET photocatalysis strategy for α-oxyamination reaction based on supramolecular confinement effect. The well-designed benzothiadiazole-based cationic monomer as energy donor and the dyes of Nile Red as acceptor are doped into the amphiphilic surfactants of sodium dodecyl sulfate (SDS). Benefitting from the supramolecular confinement space provided by SDS in aqueous environment, the FRET process between the monomer and Nile Red is effectively achieved (exciton migration rate: 3.99 × 1014 L mol‒1 s‒1). On this basis, the supramolecular FRET system is used as an efficient energy source to catalyze α-oxyamination reactions between a series of 1,3-dicarbonyl compounds and 2,2,6,6-tetramethylpiperidine-1-oxyl under white LED light, showing a yield as high as 94% and a turnover frequency value of 3.92 h‒1. This photocatalytic result shows a great enhancement compared to that of Nile Red alone.

An electrochemical method for the regeneration of trivalent iron to increase the efficiency of in-situ leaching of uranium

Due to the increasing demand for electricity with the development of production and general infrastructure, increasing the production of uranium as an economically and environmentally efficient source of energy is an urgent problem. The purpose of this study is to develop an electrochemical method for the regeneration of iron (III) ions used as a uranium oxidizer in the process of in-situ leaching of uranium minerals with sulfuric acid solutions. Methods. The mechanism of reactions in the iron (II)-iron (III) redox system was studied by recording potentiodynamic polarization curves and conducting electrolysis of the oxidation of divalent iron ions under galvanostatic conditions. Results and discussion. Cathode-anodic and anodic-cathode cyclic polarization curves taken on platinum electrodes showed that the redox reactions of iron ions are reversible and these reactions occur at a slight overvoltage. The influence of the main electrochemical parameters (current density, concentrations of iron (II) ions and sulfuric acid) on the oxidation of divalent iron ions was studied for the first time using granular anode electrodes, the electrode spaces of which are separated by an anionite membrane. It has been found that the use of granular graphite electrodes in the oxidation divalent iron ions increases the current output by more than 2 times compared to a plate graphite electrode. Conclusion. According to the results of the study, it was noted that under optimal conditions, the current output of the oxidation of divalent iron ions exceeds 90%. Extensive research has shown that trivalent iron ions, widely used in the in-situ leaching process for uranium production, can be regenerated by electrochemical methods.

Thermal effects on nonlinear vibration of nonlocal nanobeam embedded in nonlinear elastic medium

Nanotechnology has an impact on our lives in a many ways, from better medical treatments and more efficient energy sources to stronger and lighter materials and advanced electronics and this article presents the implementation of a perturbation method for the vibration analysis of simply supported and clamped–clamped Euler–Bernoulli nanobeams resting on nonlinear elastic foundations in thermal environment using nonlocal elasticity theory. Hamilton's principle is used to construct the differential equation of motion of a nanobeam in conjunction with appropriate boundary conditions. The equations of motion of the Euler–Bernoulli nanobeam are determined using nonlocal elasticity theory. It is shown how thermal loadings affect the vibration of the Euler–Bernoulli nanobeam. The multiple scale method, which is one of the perturbation method, is used to get an approximated solution for the presented system. The effects of temperature, Winkler, Pasternak and nonlinear foundation parameters on the vibration analysis of simply supported and clamped–clamped nanobeams are determined and results are given in tables and graphs.

DFT insights for structural, opto-electronic, thermodynamic and transport characteristics of Tl2TeX6 (X = At, Br, Cl, I) double perovskites for low-cost solar cell applications

The primary goal of researchers is to develop eco-friendly, sustainable, and efficient energy sources in order to address the impending energy crisis brought on by the diminution of fossil fuels. In this context, double perovskites are promising candidates to produce clean energy from solar radiation (as solar cells) and excess heat (as thermoelectric generators). In this study, we have conducted a systematic investigation of the optoelectronic, thermoelectric and thermodynamic characteristics of Tl2TeZ6 (X = astatine (At), bromine (Br), chlorine (Cl), iodine (I)) through first-principles based GGA calculations. Based on our calculations, Tl2TeZ6 (X = At, Br, Cl, I) are classified as indirect bandgap semiconductor compounds. The energy bandgaps of the aforementioned compounds exhibit an increase when the element At is substituted by I, Br and Cl. A comprehensive analysis of the optical properties has been conducted in order to assess the potential suitability of these materials for optoelectronic applications. A shift towards lower energies can be noted in the imaginary part of complex dielectric function (ε2(ω)) plots in the following progression: Tl2TeBr6, Tl2TeCl6, Tl2TeI6 and Tl2TeAt6. These double perovskites offer a wide absorption region ranging from visible to near UV regions. Tl2TeZ6 (Z = At, Br, Cl, and I) exhibits relatively low reflection of incident photons in the entire energy span (∼45 %). These compounds exhibit p-type semiconducting nature as their Seebeck coefficient values are positive. The figure of merit (ZT) values of Tl2TeX6 (X = At, Br, Cl, I) are acceptable (∼1.0) for practical high performance thermoelectric applications. The presented thermodynamic characteristics for Tl2TeX6 (X = At, Br, Cl, I) indicates that these double perovskite materials are thermally stable compounds.

Preparation and application research of transition metal phosphides

Due to the serious environmental pollution in the world, the shortcut to harmonious development is to improve traditional disposable energy and identify new energy sources that can be utilized. The current problem that human society must solve is to discover and use efficient and inexhaustible new energy sources, among which electrolytic water technology is an effective way to develop clean energy. In recent years, researchers have focused on producing hydrogen by electrolyzed water, but the intermediate hydrogen evolution reaction and the oxygen evolution reaction are relatively slow kinetic processes, and they cannot give the factory a large range of electrolytic water hydrogen production work and push down the commercialization process, so improving the rate of electrolytic water process must be an efficient catalyst. Transition metal phosphide is one of the non-precious metal catalysts in the electrochemical hydrogen evolution reaction and oxygen evolution reaction. Transition metal phosphide can promote rapid change of chemical reaction rate, and it has the characteristics of being cheap and easy to operate so it has a great prospect in the electrolysis of water. In this experiment, the oxygen evolution performance was optimized based on the crystal surface regulation of cobalt-doped transition metal nickel phosphide. The optimal reduction time and a small overpotential (60 mV) were obtained by using sodium borohydride to reduce the sample.

Model for Hydrogen Production Scheduling Optimisation

This scientific article presents a developed model for optimising the scheduling of hydrogen production processes, addressing the growing demand for efficient and sustainable energy sources. The study focuses on the integration of advanced scheduling techniques to improve the overall performance of the hydrogen electrolyser. The proposed model leverages constraint programming and satisfiability (CP-SAT) techniques to systematically analyse complex production schedules, considering factors such as production unit capacities, resource availability and energy costs. By incorporating real-world constraints, such as fluctuating energy prices and the availability of renewable energy, the optimisation model aims to improve overall operational efficiency and reduce production costs. The CP-SAT was applied to achieve more efficient control of the electrolysis process. The optimisation of the scheduling task was set for a 24 h time period with time resolutions of 1 h and 15 min. The performance of the proposed CP-SAT model in this study was then compared with the Monte Carlo Tree Search (MCTS)-based model (developed in our previous work). The CP-SAT was proven to perform better but has several limitations. The model response to the input parameter change has been analysed.

Petrophysical and Geochemical Investigation-Based Methodology for Analysis of the Multilithology of the Permian Longtan Formation in Southeastern Sichuan Basin, SW China

Against the backdrop of the national strategic goals of carbon peaking and carbon neutrality, the imperative for China’s low-carbon new energy transformation is evident. Emerging as an efficient and clean new energy source, the coal-based “three gases” (coalbed methane, tight sandstone gas, and shale gas) have gained prominence. Nevertheless, the current exploration of the coal-based “three gases” is limited to individual reservoirs, posing challenges to achieving overall extraction efficiency. The primary obstacle lies in the conspicuous disparities in gas content among different reservoirs, with the causes of such disparities remaining elusive. To address this issue, this study focused on the Permian Longtan Formation (coal, shale, and tight sandstone) in the southeastern Sichuan Basin. Through a comparative analysis of the mineral composition, organic geochemical features, and pore structure characteristics, this study aimed to delineate reservoir variations and establish a foundation for the simultaneous exploration and exploitation of the coal-based “three gases”. The research findings revealed that the differences in reservoir characteristics account for the variations in gas content among coal, shale, and tight sandstone. The mineral composition of the rock formations in the study area primarily consists of quartz, feldspar, clay minerals, pyrite, calcite, and dolomite. By comparison, the coal samples from the four major coal seams in the study area exhibited relatively large pore sizes, which are favorable for gas accumulation.

The effects of Multiwalled Carbon Nanotube to the performance of a refrigeration system

By incorporating nanofluid technology and nanolubricants into compressors, the performance can be enhanced while also lowering worldwide fuel consumption and aiming at developing cleaner, more efficient energy sources and uses. The globe is being confronted with energy security issues and heating, cooling and HVAC systems highly contribute to it. Hence, it is critical to save energy and improve the efficiency of the refrigeration cycle. This study presents experimental and theoretical findings in order to investigate the effect of Polyester (POE)-oil based multiwalled Carbon Nanotube (MWCNT) nanolubricant on the Coefficient of Performance (COP) of a refrigeration system. The objectives of this study is to analyze the stability of MWCNT nanofluids, to obtain the COP of a refrigeration cycle run with pure POE oil and MWCNT nanofluids with different concentrations respectively. The experiment was conducted by preparing 0.55, 0.65 and 0.70 g/l MWCNT nanofluid by using the two step method. The most effective concentration used in the refrigeration system was referred to the one that resulted in the highest COP. It was determined from the experiment that 0.55 g/l MWCNT nanofluid resulted in a higher COP of 5.766 as compared to the other two concentrations. Besides, it showed an improvement of 34.6% in COP as compared to the COP of using pure POE oil in the refrigeration system, which was found to be 4.285. The 0.65 g/l and 0.70 g/l concentration of MWCNT resulted in a COP of 5.618 and 5.617, respectively. The compressor work was also analyzed and was found to be reduced noticeably after adding MWCNT nanoparticles. Hence it can be concluded that the increment of MWCNT concentration in nanofluids increases the COP of the refrigeration system but only up to a certain limit of concentration.