Energy Exergy Research Articles

The effect of ambient temperature on dynamic energy–exergy analysis of a d-type boiler during cold start-up

The effect of ambient temperature on dynamic energy–exergy analysis of a d-type boiler during cold start-up

Thermodynamic assessment of a solar water heater and treatment: an energy–exergy and sustainability analysis

Thermodynamic assessment of a solar water heater and treatment: an energy–exergy and sustainability analysis

Areca nut husk nanoadditive for compression ignition engine: characterisation, energy–exergy–exergoeconomic, and sustainability analyses

Areca nut husk nanoadditive for compression ignition engine: characterisation, energy–exergy–exergoeconomic, and sustainability analyses

Energy and Exergy Analysis of an Improved Hydrogen-Based Direct Reduction Shaft Furnace Process with Waste Heat Recovery

The traditional production mode using coal as the main energy source is not conducive to the sustainable development of the iron and steel industry (ISI). The hydrogen-based direct reduction shaft furnace (HDRSF) process is a feasible technical route for promoting the green development of the ISI. However, there is a lack of comprehensive analysis with respect to the energy utilization and process flow of the HDRSF method. To address these issues, a systemic material–energy–exergy model of HDRSF is established. An improved HDRSF process incorporating waste heat recovery is also proposed, and energy consumption intensity and exergy intensity are used as assessment metrics. This study’s findings indicate that the proposed waste heat recovery can considerably lower gas demand and energy consumption intensity, but exergy intensity has little effect. The reducing gas demand drops from 2083 m3 to 1557 m3, the energy consumption intensity drops from 2.75 × 107 kJ to 1.70 × 107 kJ, and the exergy intensity drops from 1.08 × 107 kJ to 1.05 × 107 kJ when the reducing gas temperature is 900 °C, H2:CO = 1:1; meanwhile, the recovery rate of waste heat reaches 40%. This study can serve as a reference for actual HDRSF process production.

Effect of coating of waste toner powder weight concentration on absorber plate of solar still

A solar still is a device that uses sun energy to convert brackish or salted water into drinkable water and its distillate output is lower. In addition, it is the primary issue with the solar still; thus, researchers are looking for fresh ideas to raise the distillate output. The primary goal of this study is to examine the effects of mixing different weight concentrations (5%, 10%, 15%, and 20%) of toner waste powder (TWP) nanoparticles with black paint on distillate output and energy–exergy efficiency analysis. Two solar stills of similar dimensions have been used in the current study from February to March 2023 at Palanpur, Gujarat, India. Basin water, inner glass surface temperature, distillate output, and intensity of solar radiation are all monitored hourly for solar stills. This research indicates that the application of TWP coating to absorber plates increased the distillate output, and the highest distillate output of 955 ml was achieved at 10 wt. % concentration of nanoparticles, which is 40.03% higher than a conventional solar still (CSS) and 33.38%, 10.40%, and 30.64% higher than 5, 15, and 20 wt. % concentrations of nanoparticles at the same water depth, respectively. In addition, it was discovered that adding TWP to the solar still enhanced energy and exergy efficiency. Based on this research, it can be concluded that TWP is a suitable, inexpensive resource to boost energy and exergy efficiency and distillate output of solar still.

Energy exergy and economic analysis of a multiple inlet solar air heater for augmented thermohydraulic performance

Solar air heaters typically feature a single inlet connected to the absorber section. This study explores a novel design for solar air heaters by introducing multiple inlets in the absorber section, creating a double-chamber system. The square test section incorporates inlets at each corner, facilitating increased air intake and inducing a swirling motion within the test section. Air exits through either a single central vent or multiple vents in the absorber plate, entering the upper chamber. The crossflow effect and localized disturbance generated by these vents enhance turbulence inside the test section. Numerical analysis carried out using ANSYS FLUENT by considering the variations in inlet duct width and vent diameters. Optimal thermo-hydraulic efficiencies of 80.32 % and 84.5 % are achieved for the Single central vent and Multiple vents configurations, respectively, with an inlet duct width ratio of 10.0 and 3.3. While the Multiple vent configuration demonstrates lower CO2 reduction potential than the Single central vent configuration, the energy payback period is approximately 4.5 months in energy calculations and around 4 years in exergy-based calculations. The average Enviro-economic parameter is determined to be $16/year, with the highest value observed in the Reynolds number range of 9000 to 12000.

EXPERIMENTAL INVESTIGATION OF ENERGY PERFORMANCE AND EXERGY DESTRUCTION OF SIMPLE AND ROUGH-SUPERHYDROPHOBIC VAPOR CHAMBERS FOR PCB TEMPERATURE CONTROL

In this research, two vapor chambers with the same dimensions were manufactured to control the temperature of the high-power printed circuit board (PCB). In one case, the evaporator and condenser were rough and superhydrophobic, respectively. Another vapor chamber was nonrough and nonsuperhydrophobic (simple). In this study, as new experimental work, the exergy destruction analysis was performed in simple and rough-superhydrophobic vapor chambers and the effect of different parameters on exergy destruction in both vapor chambers was investigated and compared. Also, the effect of different parameters on the thermal resistance of the vapor chamber, taking into account the roughness and superhydrophobicity of the vapor chamber, was investigated and compared with the thermal resistance of the simple vapor chamber. The results showed that roughened evaporator and superhydrophobic condenser affected the amount of influence of other parameters on the thermal resistance and exergy destruction, improved the efficiency of the vapor chamber in most test cases, and reduced exergy destruction. According to the tested cases, the minimum thermal resistance and the exergy destruction were obtained as 0.18 °C/W and 13.32 W, respectively. Also, exergy destruction analysis showed that the amount of exergy destruction depended on the studied parameters in this study.

Energy, exergy and thermo-economics analyses of hybrid solar, steam turbine and biomass gasification system for hydrogen production by polymer membrane electrolyzer

This study presents an evaluation of the energy exergy and thermo-economics of a hybrid power generation system that simultaneously produces power, heat, and hydrogen using solar and biomass energy. The system employs a polymer membrane electrolyzer for hydrogen production, with heat exchangers utilized to attain the desired water temperature instead of conventional heaters. The steam turbine section is heated using exhaust gas from the combustion chamber and heated water from the condenser. Simulation of the system's thermodynamic, exergy, and exergy-economic analyses was conducted using the ESS tool. Analytical assessments were performed based on the provided data. The system achieves a power output of 25 MW, marking the highest level for solar-based systems. The results showed that the cost of the solar section, which constitutes around 68 % of the overall cost, rises with the number of mirrors. The exergy destruction rate of the entire system decreases from 25.71 MW to 24.95 MW. The total cost of operating the system increases by 175.5 dollars per hour at the highest temperature and decreases by 173 dollars per hour at the lowest temperature. The power consumption of electrolyzers directly affects the overall cost of the system, with a range of 0.05 to 0.07 MW resulting in total cost changes of 1.52 USD per hour. The transition to the work requiring the most energy by the electrolyzer causes a loss of 0.27 MW of exergy.

Numerical identifications of T-shaped rod effect on thermal performance and exergy efficiency in methane/air combustion

To maximize the power output of micro-thermophotovoltaic systems, achieving a high and uniform wall temperature is desirable. Towards this goal, this work proposes a novel combustor with inserting a T-shaped rod and assesses the effectiveness of such a strategy in determining the thermal and exergy performances with a validated computational model. Results indicate that introducing such strategy results in a 50.4 K wall temperature elevation and a 30.5 % decrease in the temperature standard deviation at the inlet velocity of 0.6 m/s. The effectiveness of applying a T-shaped rod on wall temperature is also found to be dependent on the inlet velocity. In addition, the optimal equivalence ratio associated with the highest wall temperature is shown to be stoichiometric caused by the relatively larger volumetric thermal power density. Further analysis of the pressure loss and exergy energy is performed. While the presence of a T-shaped rod can lead to an increase in the pressure loss, these are negligible relative to the ambient pressure. Furthermore, in addition to the temperature enhancement, the T-shaped rod combustor is associated with a higher exergy and exergy efficiency, which is beneficial to improving the energy efficiency of combustion devices. This work provides valuable insight into enhancing the wall temperature and energy conversion efficiency for micro-power systems.

Energy–exergy analysis for performance improvement of Brayton–Rankine combined cycle system by utilizing a solar absorption refrigeration cycle (case study: Kahnuj Combined Cycle Power Plant)

AbstractGas–steam combined cycle power plants are the most efficient electricity‐generation units based on fossil fuels. However, these power plants are prone to efficiency decrease in hot climates as high ambient temperatures adversely influence the gas turbine's output. The present study investigated the effect of incorporating a solar absorption refrigeration (SAR) system into an actual combined cycle power plant for the first time. First, the energy and exergy analyses were performed using THERMOFLOW software. Then, the influence of the ambient temperature (10°C–52.5°C) on the power plant's performance and its components was investigated. The SAR system was then used to cool the compressor's input air and improve the power generation capacity by employing TRNSYS software. The results showed that the power plant reached its maximum efficiency at an ambient temperature of 26.6°C. However, its overall efficiency and net power generation were dropped with a further increase in the ambient temperature. Employing the SAR system for each gas turbine in the power plant on a sunny day until 2 p.m. would decrease the compressor's input air temperature. For example, for the refrigeration capacities of 450, 700, and 1000 tons for each gas turbine, the temperature was reduced by nearly 3°C, 5°C, and 7°C, respectively. Under the same condition, power generation capacity improved by 12.5, 24, and 32.5 MW, and the overall efficiency rose by 0.6%, 1.4%, and 2%. Such an increase in power and efficiency occurred during peak demand, which was significant.

Energy, exergy, sustainability evaluation of the usage of pyrolytic oil and conventional fuels in diesel engines

Solid wastes like used tires have high annual production and significant environmental impact potential. Tire wastes can be pyrolyzed to regenerate energy and create useful products. The purpose of this study is to demonstrate the use of pyrolytic oil produced by the pyrolysis of waste tires as fuel in diesel engines. The energy exergy and sustainability of pyrolytic oil and conventional marine diesel fuels were examined in this study. The energy was determined in the experimental processes used to transform used tires into carbon black, pyrolytic oil, and pyrolytic gas. The components of SOX, NOX, and CO2 produced when pyrolytic oil and conventional marine fuels were combusted in diesel engines were obtained. As a result of the study, the energy value of the pyrolytic oil produced during the pyrolysis process as fuel was determined to be 2.8 MW. The results indicated that the combustion of pyrolytic oil in diesel engines had a thermal efficiency of 38% and a second-law efficiency of 58%. The standard marine fuels were found to have a sustainability index of 2.7, while pyrolytic oil had a sustainability index of 1.42.

Improving the Performance of Unglazed Solar Air Heating Walls Using Mesh Packing and Nano-Enhanced Absorber Coating: An Energy–Exergy and Enviro-Economic Assessment

This study aims to upgrade the effectiveness of unglazed solar air heating walls (SWs) using mesh packing and nano-enhanced black paint. In this regard, two SW cases with 10 cm and 15 cm plenum thicknesses have been fabricated and tested simultaneously with different modifications. In other words, six different SW configurations have been designed and empirically investigated in this research. Unmodified SWs with two plenum thicknesses have been tested in the first experiment. Iron meshes have been utilized in both SWs in the second test. In the third experiment, the impact of the combined usage of mesh packing and Fe (iron) nanoparticle-enhanced black paint (absorber coating) at 2% w/w concentration on the performance has been evaluated. Experimental results exhibited that the combined usage of mesh packing and nano-doped paint in the SWs with 10 cm and 15 cm plenum thicknesses improved the average effective efficiency value by 29.54% and 31.20%, respectively, compared to the unmodified cases. Also, the average exergy efficiencies of the six tested SW configurations were attained in the range of 6.24–12.29%. Moreover, the findings of this study showed that reducing the plenum thickness and applying the combination of meshes and nano-coating improved the annual carbon dioxide savings by 44.72%.

Plastic Waste Upcycling for Generation of Power and Methanol: Process Simulation and Energy–Exergy–Economic (3E) Analysis

Plastic Waste Upcycling for Generation of Power and Methanol: Process Simulation and Energy–Exergy–Economic (3E) Analysis

A review of studies on air-breathing turbine engines from an energy–exergy viewpoint

A review of studies on air-breathing turbine engines from an energy–exergy viewpoint

Experimental performance evaluation of solar still with zig-zag shape air cooled condenser: An energy–exergy analysis approach

In the present experimental effort is made to increase the performance of a solar still (SS) by including a novel design of a zig-zag-shaped air-cooled condenser (ZZACC) and cuprous oxide (CuO) as a nanomaterial. Research work is conducted in the climatic conditions of Gandhinagar, Gujarat, India, from September to November 2020. A comparison was made to assess the performance of a conventional solar still (CSS) and a solar still equipped with a zig-zag shape air-cooled condenser (SSWZZACC) with CuO. The experiments’ findings showed that adding CuO to SSWZZACC increases the distillate production by 46.83% and the daily energy efficiency by 45.98%, respectively, compared to CSS. Also, SSWZZACC demonstrates a better efficiency of exergy and latent heat of vaporization than CSS because CuO causes an increase in the evaporative heat transfer coefficient of water. In life cycle cost analysis study discovered that SSWZZACC has a 27.77% lower cost per litre of water (CPL) than CSS. The obtained maximum energy and exergy efficiency values for CSS and SSWZZACC were 2.36% & 25.75% and 3.9% & 37.59%, respectively. In economic and environmental aspects, it was found that SSWZZACC with CuO showed a cost-effective desalination unit and was highly effective from a carbon credit point of view (CCP) by CO2 mitigation.

Energy exergy and economic evaluation of a CCHP configuration powered by CPVT collectors dynamically

This study presents a dynamic simulation of a combined cooling, heating, and power (CCHP) configuration powered by concentrating photovoltaic thermal (CPVT) collectors. The desired configuration comprises CPVT collectors, a phase change material (PCM) storage tank, an organic Rankine cycle (ORC), an absorption chiller, and heat exchangers. The evaluation has been carried out for a residential building using EES, MATLAB, and TRNSYS software. Moreover, an auxiliary heater has been used to provide the thermal energy of the desired configuration in case of low or no solar irradiation. The desired configuration has been evaluated from energy, exergy, and economic points of view during the warm months of the year (May to September). Also, the influences of key parameters of the desired system such as the CPVT area, CPVT flow rate, and PCM melting temperature on the performance of the desired configuration have been examined. The results indicate that the solar fraction enhances by about 161 % when the CPVT area changes from 100 m2 to 400 m2. Also, CPVT has found to be the main contributor to exergy destruction, accounting for 49% of the total. The maximum energy and exergy efficiencies of the desired configuration are obtained at the CPVT area of 400 m2 with values of 72.26 % and 79.03 % respectively. On the other hand, the lowest payback period occurs at 100 m2 with value of 11 years.

Thermal analysis of a rotating fluidized bed dryer in static geometry dryer with and without slit

A rotating fluidized bed in a static geometry dryer without a slit is highly recommended in multiple operations, such as separation, mixing, gasification, combustion, particle coating, and drying process intensification. The present analysis proposed a highly efficient moisture removal technique into optimized energy forms, including electrical and thermal energy used in air heating and particle fluidization. Hence, to reduce a considerable energy loss in rotating fluidized bed chambers, the energy exergy analysis of granular drying is carried out for two distinct drying chambers without and with a slit. Granular drying has been conducted in dryers at 55 °C –65 °C, airflow rate of 400–600 m3/h, drying inventory of 300–500 g, energy utilized, and energy utilization ratio. It is observed that. In the slit-less rotating fluidized bed with static geometry dryer, the drying efficiency is increased by 5.6%, the drying cost decreased by 19.8%, and the payback period is reduced by 54% compared to the rotating fluidized bed dryer in static geometry.

Extended exergy accounting for assessing the sustainability of agriculture: A case study of Hebei Province, China

Along with the growing demand and improving diet, the agricultural sector faces challenges in balancing resource consumption, environmental impacts and yields. This study presents an extended exergy accounting to capture the changing characteristics of the usefulness of resources in the agricultural sector of Hebei Province during 2000–2018 from thermodynamics perspective. The accounting includes exergy fluxes of energy, materials, environmental remediation, labor, capital and yields quantified by joules. The agricultural sector of Hebei Province comprising the cropping, forestry, stockbreeding and fishery sub industries, has experienced transformation into a modern pattern. The results showed that (1) the extended exergy in the agricultural sector of Hebei Province exhibited a declining trend; the natural resource exergy, particularly energy exergy, dominated the investments in the sector. (2) The capital exergy, labor exergy and environmental remediation exergy all decreased; the capital exergy and labor exergy decreased more than the environmental remediation exergy. The shares of the labor exergy from the services of agriculture declined, while those of the labor exergy from forestry and stockbreeding notably increased. (3) Since the cropping accounts for a large part of the yields, the large quantity of crop residues should be considered seriously. The potential of the other three sub industries was very high. The comparison between the agricultural sector in Hebei Province and that in China as a whole involving exergy indicators showed that Hebei Province was more modernized and had achieved great progresses. Extended exergy accounting captures the agro ecological economic system to help identify resource depletion and environmental costs in other areas or industries from a sustainable development perspective.

Comparison of the performance of a modified temperature-controlled microwave dryer to improve heat-mass transfer, increase energy efficiency and preserve quality characteristics of shad (Alosa fallax nilotica)

In this study, shad (Alosa fallax nilotica) was dried in microwave (360, 720 W), developed heat controlled microwave (50, 70 °C), hybrid microwave (350 W + 50 °C, 350 W + 70 °C) dryers. Drying time, drying rate-rate, effective diffusion, color, hardness, energy consumption (SMER, SEC), exergy energy, energy efficiency, heat-mass transfer value of the drying processes were investigated. The shortest drying process was determined as 450 seconds at 720 W power, while the longest was 414minutes at 50 °C. Effective diffusion values calculated for microwave, temperature controlled microwave and hybrid drying processes are 1.32–9.43 × 10−8 m2/s, 2.43 × 10−8-2.41 × 10−7 m2/s and 8.52 × 10−7-2.76 × 10−6 m2/s, respectively. Has changed between It has been determined that the most suitable drying method in terms of total energy consumption and energy efficiency values is the drying process performed in a temperature-controlled microwave dryer. Exin and Exout values of the temperature-controlled microwave drying process were calculated to vary between 2.20 and 5.16 J/s and 1.82–4.68 J/s, respectively. Exin and Exout values of the hybrid drying process were calculated to vary between 1.94 and 4.84 J/s and 1.70–4.68 J/s, respectively. The heat transfer values calculated for the temperature-controlled drying process varied between 0.104 and 0.00269 W/m2K and the heat transfer values calculated for the hybrid drying process ranged between 0.100 and 0.00270 W/m2K. It was determined that the most suitable drying processes for color characteristics were 360 W and 350 W + 50 °C. For the hardness value, it was determined that the 350 W + 70 °C drying process was statistically more appropriate (P < 0.05).

Determination of the sustainability index along with energy–exergy–emission–economic analysis of a VCR diesel engine fuelled with diesel–bioethanol–Al2O3 nanoparticles

Different percentages of bioethanols made from waste rice straw blended with diesel mixed with Al2O3 nanoparticles were tested in a VCR CI engine under varying load intensities and at different compression ratios.