Second Figure Of Merit Research Articles

Graphene Coating and its Effect on Performance of Box Type Solar Cooker: An Experimental Investigation

Background: Solar cookers have been the subject of several theoretical and empirical investigations, with numerous modifications attempted to increase efficiency and security. Solar cookers need much sophisticated research and enhancement work to function better. A thorough grasp of the application of graphene in box-type solar cooking systems is crucial for both solar energy and graphene. Objective: To improve the performance of box-type solar cookers, this patent research aims to offer an experimental investigation and insightful information on of applying graphene coating to the absorber plate and its derivative. Materials and Methods: To ensure equal dispersion of graphene into the black paint, three samples containing (1, 3, and 5wt%) of graphene embedded with the paint were produced with 1mm, 3mm, and 5mm thickness of the coating and stirred at 400 rpm for two hours using a magnetic stirrer. Xray diffraction and scanning electron microscopy have been studied to comprehend the influence of graphene nanoparticles on the surface morphology of the coated absorber panel. Performance evaluations of the box-type solar cookers were conducted with and without a graphene coating on the absorber plate, and data has been recorded for each case. Results: The results of patent research show that the absorber plate with (1, 3, and 5wt.%) of graphene embedded with black paint 1mm, 3mm, and 5mm thickness coating has a maximum thermal efficiency of 41.48% with 97.08 W cooking power, 46% with 109.35 W cooking power, and 49% with 114.77 W cooking power for the average solar irradiation is 978 W/m2. Discussion: It was determined that the cooking power (P), the first figure of merit (F1), and the second figure of merit (F2) were all satisfactorily achieved. Embedding black paint into graphene coating has been shown to significantly influence the heat transmission and thermal performance enhancement of box-type solar cookers, as demonstrated by the findings of X-ray diffraction and Scanning Electron Microscopy analysis. Conclusion: The current research makes it abundantly evident that the incorporation of graphene into the absorber plate of a box-type solar cooker, together with the application of a black paint coating, leads to increased heat transfer rates, which in turn provides an increase in cooking power. Because of this, graphene is an attractive nanomaterial that has the potential to improve the performance of box-type solar cookers, which is the novelty of this research work.

Enhancement the solar box cooker performance using steel fibers

AbstractThe use of fossil fuel and wood for cooking poses health, environmental, and economic challenges, especially with the growing population. This has led to an increase in the trend towards the use of clean and sustainable cooking sources, including solar cookers. This experimental study aims to contribute by enhancing the performance of a solar box cooker (SBC) according to the concept of porous media via adding steel fibers inside the box as a modified SBC and comparing it with a conventional SBC. The stagnation test to determine the first figure of merit and the load test to determine the second figure of merit, standard boiling time, and cooker optothermal ratio were conducted under the outdoor conditions of Baghdad city. Also, an energy and exergy efficiency analysis, and calculating the rate of heat loss by three water loads heating and cooling tests. The results revealed that the modified SBC has a higher thermal performance than the conventional SBC.

THERMAL PERFORMANCE OF DUAL-OPERATED SOLAR COOKING AND DRYING SYSTEM

In this work, the thermal efficiency of a dual-operated solar cooking and drying system that may be utilized for domestic use was examined. An analysis of the system’s thermal performance was conducted at Sokoto Energy Research Centre (SERC) using the Bureau of Indian Standards (BIS). Sampling cooking and drying tests were carried out, and the potential for extended cooking time for brine solution and animal fat was conducted. The results showed that the first figure of merit (F1) value agrees with the standard value of 0.12 and the second figure of merit (F2) value is in close correspondence with 0.25 (BIS Standard). The system was able to dehydrate 89 % of the moisture content of banana slices weighing 118 g which is of uniform thickness of 4 mm to achieve a stable weight of 12 g after 8 hours of drying. Animal fat showed more potential for extended cooking time than brine solution, as it took 5 hours to cool after heating for about 3 hours. Six pieces of eggs were boiled for 45 minutes in a temperature range of 29.7 oC and 88.2 oC. These findings indicate the potential of this dual-operated system for domestic applications.

Thermal performance enhancement on a box-type solar cooker using a triangular fin over a conventional cooking pot

The thermal performance of existing box-type solar cookers is limited and to improve the performance many research works reported on modification of solar cooker sub-systems i.e., cylindrical fin over the cooking pot, extra air duct, integrating with a photovoltaic panel, incorporation of heat storage materials and multiple reflectors. This paper presents a novel study of a triangular-finned cooking pot to increase the convective heat transfer rate and solar irradiance over the cooking pot. The thermal network diagram is presented and thermal losses are measured using MATLAB. The thermal visualization is presented with the help of COMSOL Multiphysics 5.5 and uncertainty analysis of different performance parameters is completed with Engineering Equation Solver (EES). The simulation results found thermal losses occur from the top, bottom and side are 4.26, 0.77 and 0.64 W/m2 respectively. The experimentally observed result indicates the cooking time is reduced from 94–95 min to 85–86 min during the boiling test of 1.5 kg water for the triangular finned cooking pot. The first figure of merit is 0.139 and the second figure of merit is 0.563 respectively for the same loading conditions. The cooking power is increased from 68.71 W to 77.06 W. The thermal efficiency is increased from 36.16 % to 40.55 %. The uncertainty analysis emphasizes the value of the performance parameter lies within an acceptable range. From thermal visualization, It is concluded that wall edges are less affected by heat flow and the correct placement of the cooking pot is necessary for uniform heating.

Comparative performance evaluation of modified solar cookers for subtropical climate conditions

Solar cooking has been an attractive way of cooking food using solar energy (which is a form of renewable energy). Two modified solar cookers namely ‘Modified solar cooker with an inclined cover (MSCIC)’, and ‘Modified solar cooker (MSC)’ have been designed and tested for the climatic condition of Prayagraj, Uttar Pradesh, India. The present work evaluates the thermal performance of two transparent solar cookers with the same aperture area but with different geometries. The experiments have been conducted with same quantities of water taken in the pots of both the cookers. The effect of various thermal parameters such as ‘pot water temperature’, ‘figure of merits’, ‘thermal efficiency’, ‘energy and exergy’ with a comparative analysis of modified solar cookers have been analysed. Results show that the First figure of merit for both transparent cookers have been found nearly identical (F1MSCIC = 0.11 and F1MSC = 0.106) and Second figure of merit have been found F2_MSCIC = 0.77 and F2_MSC = 0.72. Similarly, instantaneous exergy and energy efficiencies have been found 6.1% and 7.8% respectively for MSCIC, and 4.6% and 7.2% respectively for MSC. This indicates that thermal performances of both cookers were comparable. A fair acceptable agreement was found between MSCIC and MSC experimental results also.

Performance analysis of parabolic dish solar cooking system with improved receiver designs

Lack of access to clean energy for cooking and heating applications is one of the challenges faced by households in developing countries. Solar cooking is one of the solutions, but suffers low adoption and utilization due to various challenges including technical limitation. This study investigated initiatives on improving the technical viability of parabolic dish solar system used for direct cooking by focusing on the receiver. Three receiver prototypes namely; Insulated, Oil-filled and Air-filled, all incorporated with a base circular ring, were constructed and their performance was compared experimentally with the conventional receiver. The maximum temperature inside cooking vessels were 154 °C, 99 °C, 141 °C and 128 °C while standardized stagnation temperature and first figure of merit (F1) were found to be 159 °C, 100 °C, 154 °C and 109 °C; and 0.26, 0.15, 0.54 and 0.17, for systems with insulated receiver, oil-filled receiver, air-filled receiver, and conventional receiver, respectively. The second figure of merit (F2), overall heat loss factor, heat exchange factor and optical efficiency were determined as 0.36, 0.15, 0.14 and 0.33; 59.7 W/m2 K, 28.6 W/m2 K, 20.49 W/m2 K and 73.4 W/m2 K; 0.18, 0.75, 0.69 and 0.23; 25%, 4%, 4% and 17%. The study found that the cooking system with Insulated Receiver gave more merits and was established as the best.

Experimental investigation of the effect of reflectors on thermal performance of box type solar cooker

Cooking consumes a tremendous amount of energy on a regular basis. Solar energy is a very versatile and free energy source that could be used for different applications, including solar cooking. The aim this study is intended to experimentally investigate the effect of different reflectors on the performance of solar box cookers. Box-type solar cooker has been produced and tested with no reflector, aluminum foil reflectors, and mirror glass reflectors cases. Load and no-load tests have been conducted for all three reflector cases and the performances of cookers for each cases reflector have been determined. Several cooking tests was conducted in the outdoors, to investigate the thermal performance of the cooker using water as the absorbing medium. The results of the experimental demonstrate that, the cooker with three side mirror glass reflectors could reach a reasonably high temperature with better efficiency. 1.5 kg of water boiled in 51 min and its second figure of merit was found as 0.533 using mirror glass reflectors. The mirror glass reflector increases the efficiency of the experimental box-type solar cooker by 134% as compared with the cooker having no reflector. The experimental cooker with no reflector did not boil water during the testing period, so it is not recommended for cooking applications; whereas the cooker with the mirror glass reflector has been confirmed to cook most Ethiopian dishes with reasonable performance.

Thermal analysis of a box type solar cooker coupled with Fresnel lens

The thermal analysis of a Box-type solar cooker (BTSC) coupled with two Fresnel lens magnifiers (FLMG) is presented in this paper. A time dependent numerical model based on heat balances occurring at different parts of the cooker was prepared and executed in a MATLAB program. To check the robustness of the model, the temperature variation of the cooker elements obtained by the mathematic modeling was compared with the experimental results. The comparison showed the average estimated error between the experimental and numerical values fell between 0.73–3.49 percentage. In order to check the effectiveness of the FLMG, First Figure of merit (F1) and Second figure of merit (F2) tests were performed as per international testing procedures. The first figure of merit value increased from 0.11 to 0.12 m2 °C/W, converting the BTSC from B grade category to A grade. The Second figure of merit rose from 0.43 to 0.45 by utilizing the FLMG, indicating the improvement in heat exchange to the load in the cooking vessel. The temperature of all the components of the BTSC was increased by incorporating the FLMG. The paper also discusses the variation of different heat transfer coefficients coming to play in the cooker. Basmati rice was successfully cooked by the solar cooker in an interval of 58 min.

Thermal performance assessment of a cylindrical box solar cooker fitted with decahedron outer reflector

One of the important issues humankind globally faces in recent years is the scarcity of non-renewable energy resources. Solar energy is considered safe and renewable, which can fulfil the demand and supply chain requirements. Solar box cookers (SBCs) are popular in domestic cooking due to their ease of use and handling. The prime objective of the present work is to develop and test the performance of a cylindrical SBC fitted with decahedron-shaped reflector (CSBC-FDR). The CSBC is designed using minimum entropy generation (MEG) method. Through experiments, we observed that absorber plate attains peak temperature of about 138°C–150°C with the aid of decahedron reflector. The first figure of merit (F1) is found to be 0.13, indicating better optical efficiency and low heat loss coefficient for the SBC. The second figure of merit (F2) is obtained as 0.39, which indicates good heat exchange efficiency (F') and less heat capacity for cooker's interior. The average energy efficiency, exergy efficiency, and standardized cooking power values are 21.93%, 3.04%, and 25.28W, respectively. These results show that the present CSBC-FDR is able to cook food in a shorter period with better efficiency. The experimental and numerical values of overall heat loss coefficient of the developed SBC are in close agreement. The experimentally assessed performance parameters reveal superior performance of the present cylindrical SBC in comparison with many conventional rectangular and trapezoidal box solar cookers.

Experimental and numerical analysis of tiltable box-type solar cooker with tracking mechanism

A tiltable box-type solar cooker was designed and fabricated to meet the cooking needs of a typical family of five in Sana'a, Yemen, which is currently experiencing an energy crisis as a result of the war that has been ongoing since 2015. The production cost of the cooker is US$74, which is affordable to Yemenis. The first figure of merit (F1), second figure of merit (F2), cooking power, and maximum stagnation temperature were found experimentally to be 0.1354 °Cm2/W, 0.4934, 63.53 W, and 172.75 °C, respectively. A numerical simulation with a solar load model was performed using ANSYS-FLUENT Academic 2019 R3 to study the temperature distribution and solar heat flux inside the cooker. The solar beam direction and radiation were considered via the solar load model using two methods: by defining the experimental data as the input and by using ANSYS-FLUENT's solar calculator. The simulation results were validated by comparison with experimental results in the form of temperature measurements, and good agreement was observed between the numerical and experimental results with a maximum error of 3.29%.

Thermal Performance Comparison and Augmentation of Two Identical Box-Type Solar Cookers Operating in Tropical Climatic Conditions

Abstract In the present study, experimental studies have been performed to compare the thermal performance of two geometrically identical box type solar (B-T-S) cookers. To carry out this aim, the thermal performance of BTS cooker in terms of figure of merits, namely, first figure of merit (F1) and second figure of merit (F2) are calculated for both cookers as specified by the Bureau of Indian Standards (BIS). At no-load condition (i.e., stagnation test), it is found that first figure of merit for both cookers that is cooker 1 and cooker 2 is around 0.12. This implies that both the cookers are identical in thermal performance. In addition to this, the effect of lugs height, reflector, number of pots, and load on B-T-S cooker performance have also been investigated. From the results and discussion, it is concluded that the use of lugs reduced the heat transfer rate between cooking pot and absorber plate. Further, it is found that the pot content temperature is enhanced by 25.5% and 23.4% by using mirror and aluminum reflector with cooker, respectively. However, it is observed that the performance parameters of B-T-S cooker in terms of F2 increases linearly with the increase of number of cooking pot (with correlation F2 = 0.0316n + 0.2238, where n is the number of pots) and load (correlation as F2 = 0.0451 m + 0.1844, where m is the mass of water in cooking pot) on the pot.

Solar cooking in Ethiopia: Experimental testing and performance evaluation of SK14 solar cooker

Fuel-wood shortage is a rising issue that has so far been frequently addressed. Solar cooking is a promising solution to firewood dependency, and the prettiest method to exploit solar energy. The objective of this paper is to manufacture and testing of the performance of SK14 solar cooker under the Ethiopian climate. The cooker was contrived from market available flat iron and reflective aluminum sheets having a reflective index of 0.9. Experimental tests without and with load were carried out. The performance tests were conducted on March 1st and March 13th, 2020 in Bahir Dar, Ethiopia. The no-load test results revealed that the maximum temperature, stagnation temperature inside the midpoint of the cooking pot and first figure of merit were 212 °C, 188 °C, and 0.22 °C/W/m2 respectively. The load tests have shown that the cooking power, standard cooking power, thermal efficiency, and second figure of merit are 635 W, 375.8 W, 46.4%, and 0.625 respectively. The cooling test also showed an optical efficiency of 51.59 and heat loss factors of 0.328. In conclusion, cooking power and achieved temperature acquired by SK14 confirms cooking of common Ethiopian dishes with great flexibility.

Experimental investigation of a box-type solar cooker incorporated with Fresnel lens magnifier

ABSTRACT The study was conducted to evaluate the thermal performance of a box-type solar cooker (BTSC) by implementing two Fresnel lens magnifiers (FLMG) which concentrate the solar irradiance on to the cooker surface. A comparison in thermal performance was done in the presence and absence of the Fresnel lens magnifier. Three main tests, namely, stagnation test, load test, and cooking power test were conducted for determining the performance. It was seen that the first and second figure of merit increased from 0.11 to 0.12ᵒCm2/W and 0.43 to 0.45 respectively in the presence of the Fresnel lens magnifier. A linear regression analysis of the plotted points was used to develop a relationship between standardized cooking power and temperature difference and the cooking power for a temperature difference of 50ᵒC was calculated. The cooking power enhanced from 43.83 W to 46.87 W at the temperature difference of 50ᵒC by the usage of the magnifier. The average value of transmittance for the magnifier was 72.26% for the solar energy spectrum. The geometrical concentration ratio was increased by 48.7% by incorporating the Fresnel lens magnifier. The average value of energy efficiency of the solar cooker was calculated and was found to increase from 29.6% to 32.04% by adding the Fresnel lens magnifier.

Explicit and Efficient WOM Codes of Finite Length

Write-once memory (WOM) is a storage device consisting of binary cells that can only increase their levels. A $t$ -write WOM code is a coding scheme that makes it possible to write $t$ times to a WOM without decreasing the levels of any of the cells. The sum-rate of a WOM code is the ratio between the total number of bits written to the memory during the $t$ writes and the number of cells. It is known that the maximum possible sum-rate of a $t$ -write WOM code is $\log (t+1)$ . This is also an achievable upper bound, both by information-theoretic arguments and through explicit constructions. While existing constructions of WOM codes are targeted at the sum-rate, we consider here two more figures of merit. The first one is the complexity of the encoding and decoding maps. The second figure of merit is the convergence rate , defined as the minimum code length $n(\delta)$ required to reach a point that is $\delta $ -close to the capacity region. One of our main results in this paper is a capacity-achieving construction of two-write WOM codes which has polynomial encoding/decoding complexity while the block length $n(\delta)$ required to be $\delta $ -close to capacity is significantly smaller than existing constructions. Using these two-write WOM codes, we then obtain three-write WOM codes that approach a sum-rate of 1.809 at relatively short block lengths. We also provide several explicit constructions of finite length three-write WOM codes; in particular, we achieve a sum-rate of 1.716 by using only 93 cells. Finally, we modify our two-write WOM codes to construct $\epsilon $ -error WOM codes of high rates and small probability of failure.

Development and Performance Evaluation of High Insulation Box Type Solar Cooker

This paper presents the design, development and performance evaluation of high insulation box type solar cooker. The solar cooker is capable of boiling food for five persons per day. Stagnation test and the water boiling test of the solar cooker were performed during April, 2017. The resulting values of first figure of merit (F1 ), second figure of merit (F2 ) and standardized cooking power (Ps ) was 0.1200 C, 0.424 and 45 W, respectively, which categorized the cooker as class A. This high insulation solar cooker was found to have high values of F1 and F2 (F1 >0.12 and F2 >0.40) during different seasons of the year. The overall efficiency of the high insulation box type solar cooker was 26.5%. The cooker is estimated to save 1293.8 MJ of energy per year. The cost of the cooker is INR 4500.00. The payback period of the solar cooker as compared to firewood, electricity, coal, LPG and kerosene based cooking was estimated to be 1.49, 1.94, 2.42, 3.12 and 6.99 years, respectively. The high insulation box type solar cooker can reduce about 815.30 kg of CO2 emission on annual basis.

DEVELOPMENT AND THERMAL PERFORMANCE ANALYSIS EVALUATION OF A TRUNCATED PYRAMID SOLAR COOKER

Study aimed to develop and evaluate the thermal performance of truncated pyramid solar cooker viz non-modified and modified. Tests have been carried out in Department of Agricultural Engineering, Faculty of Agriculture, Ain Shams University, Shubra El-Kheima, Egypt (Latitude 30o11’ N, Longitude 31o24’ E). The solar cookers were not loaded, and loaded with 0.5, 1.0 and 2.0 liter of water. The modified truncated pyramid was filled with different quantities of rice. The thermal performance was evaluated by using first figure of Merit, second figure of Merit and energy efficiency. textural properties of rice and biscuits and cost analysis were measured. The absorber plate temperature of the modified was 51. 8 % higher than the absorber plate temperature of the non-modified cooker. The calculated values of first figure of Merit was 0.102 and 0.08 oC.m2/W with modified and non-modified truncated pyramid cooker types, respectively. The value of second figure of Merit was 0.239 and 0.523 for modified and non-modified truncated pyramid cooker, respectively.

Performance Evaluation of a Solar Cooker with Low Cost Heat Storage Material

A solar box cooker (SBC) has been developed for the thermal performance evaluation by operating it on a low cost thermal storage. For this, a mixture of sand and granular carbon has been prepared and tested for an optimum ratio under a solar collector. After testing, the ratio of 4:6 (sand: carbon) has been observed to maintain a high temperature range with long term heat storage. This mixture has been used as thermal heat storage inside the SBC. The experimentation procedure has been conducted under climatic conditions of Moradabad, India. Results indicated that the first Figure of merit (F1) was 0.13 m2°C /W, second Figure of merit (F2) was 0.44 m2°C /W, thermal efficiency was estimated to be 37.1%, cooking power was estimated as 44.81% and overall heat loss coefficient was 3.01 W/m2°C. The system was found feasible for cooking during the off sunshine conditions.

Investigating the Effect of Different Heat Storage Media on the Thermal Performances of Double Exposure Box-type Solar Cookers

This paper investigates the effect of some heat storage materials on the thermal performances of double exposure box-type solar cookers. Benzoic acid, stearic acid and vegetable oil were used in storing heat in double exposure box-type solar cookers. Using standard methods, some thermal performance parameters were evaluated and compared to a control design (no heat storage). The average first figure of merit were; 0.13, 0.14, 0.12 and 0.11 ℃ m-2 W-1 for benzoic acid, control, stearic acid and vegetable oil cookers, respectively, while their respective second figure of merit were; 0.45, 0.40, 0.10 and 0.12. Benzoic acid influenced a higher thermal performance while stearic acid and vegetable oil had a reduction effect. Benzoic acid and vegetable oil had significant effect on the cooking power of the solar cookers while stearic acid had effect on the first figure of merit.

Evaluating the optimum load range for box-type solar cookers

This paper introduces a new concept of Optimum Load Range (OLR) for solar cookers. OLR gives the load values for which cooker preferably shows good thermal as well as good cooking performance; it may be considered a crucial parameter for solar cookers. This OLR concept is based on the dependence of rate of rise of load temperature on different heat transfer processes between load and cooker interior. This concept illustrates solar cooking in two simple steps. The total time required to complete these steps puts an essential constraint for cooking of any load amount. The maximum value of load (upper limit of OLR) till which cooker shows satisfactory cooking may be determined from this constraint. This constraint requires determination of two OLR parameters which are tstep I and tstep II. The load for which cooker remain almost 30% efficient, may be referred as lower limit (minimum value) of OLR. For the verification of OLR, experimental studies have been conducted with a solar cooker named SFSC. The OLR parameters along with different thermal performance parameters (TPPs) (second figure of merit (F2), utilization efficiency (ηu) etc.) suggested by different researches for solar cookers in water load condition have been computed from the measured thermal profiles of different loads (0.8–3.0 kg). From the curve analysis of different TPPs with load, the existence of upper limit of OLR is observed. The values of rate of rise of load temperature at water temperatures 80, 85 and 90 °C for different loads also confirm the same. The OLR of SFSC is found to be 1.2–1.6 kg.

Novel solar cookers: suitable for small families

This paper presents the fabrication details and on-field experimental studies of two novel solar cookers, suitable for cooking requirements of small families; these are named as small family solar cookers (SFSC-1 and SFSC-2). Small size, good thermal performance, light weight, low-cost and short payback periods are some important features of these cookers. The values of some essential thermal performance parameters, first figure of merit (F1), second figure of merit (F2) and standard cooking power suggested by Bureau of Indian Standards and International Standard for box-type solar cookers, have been evaluated by experimental studies and found to be 0.116°C m2/W, 0.466, 30 W and 0.118°C m2/W, 0.488, 50 W for SFSC-1 and SFSC-2, respectively. A comparative analysis of the thermal performances of SFSCs with the solar cookers, developed by many authors, has also been presented here. The payback periods with respect to different cooking fuels for SFSCs have been found to be reasonably short.