Solar pond technology is an effective and most economical way to convert and store solar thermal energy. In this paper, numerical and experimental studies were conducted to investigate the energy distribution and efficiency in the inner zones of an inverted truncated pyramid shaped solar pond. For this purpose, a small-scale solar pond was built and tested at Karshi State Technical University. The height of the solar pond is 1.5 m, the lower and upper bases are 0.7 m and 1.5 m, respectively. The volume is approximately 2 m3.

Purpose This study begins by outlining the core principles of how flat plate solar collectors (FPSC) operate and the underlying mechanisms of heat transfer. It underscores the pivotal role of fin patterns in enhancing convective heat transfer. Design/methodology/approach The primary objective is to examine the impact of diverse fin patterns on the thermal performance of FPSCs. The study involves the development of a 3D-CFD model for FPSC using the computational fluid dynamics (CFD) software ANSYS FLUENT. The analysis is conducted for variable mass flow rates (mf) ranging from 0.01 to 0.05 kg/s with an interval of 0.02 kg/s. Each flow rate is assessed for three distinct fin patterns: straight plate fins, V-shaped fins and wavy fins. Recognizing the variation in solar radiation intensity throughout the day, the analysis is executed at six different time points ranging 10:00 a.m. to 03.00 p.m. with a time interval of 1.00 h. Findings It is observed that the wavy fin pattern with a mass flow rate of 0.01 kg/s exhibited the highest outlet temperature, showing a significant temperature difference of 12.4 K at noon. Conversely, the V-shaped fin pattern with a mf of 0.05 kg/s has the lowest temperature difference value, measuring only 3 K. The analysis included the calculation of thermal efficiency for each case, revealing that the V-shaped fin pattern at a mf of 0.05 kg/s and a sun radiation intensity of 885.42 W/m2 achieved the maximum instantaneous thermal efficiency (ηth) of 34.7%. The study records the outlet air temperature for all of these combinations and presents the data graphically in the paper. Originality/value The findings of the simulations indicate that the thermal performance that is ηth and maximum temperature of outlet air of FPSCs can be improved through the utilization of variable fin patterns.

Solar energy is a key renewable energy source. Research and development have focused on enhancing the heat transfer coefficient, heat gain, and practical efficiency of solar systems. The aim of this study is to evaluate the performance of a flat solar panel collector using a nanofluid under conditions in the city of Kirkuk/Iraq, 35° latitude and 45° longitude, in terms of practical calculation of thermal efficiency. The study included making two solar collectors, one traditional and the other improved using a nanofluid (CuO). The CuO/Water nanofluid was prepared with a volumetric concentration of 0.25 % by mechanical mixing and then ultrasonic mixing to homogenise the particles and eliminate the agglomerations that form inside the fluid. Practical testing was conducted for the two solar collectors, one using distilled water and the other using the nanofluid, during four months (January, February, March, and April) of the year 2023. The experiments revealed that the efficiency progressively improves from 9:00 a.m. to 1:00 p.m. This increase is attributed to solar radiation’s decreasing intensity post 12:00 p.m., while thermal storage and minimised thermal losses continue to contribute. After 2:00 p.m., the efficiency dwindles due to the declining solar radiation intensity. The practical efficiency of a 0.25 % nanofluid (CuO) attains its zenith at a mass flow rate of 0.015 ls−1. Higher mass flow rates enhance heat transfer within fluid-filled tubes. The collector efficiency at this flow rate ranges from 31.66 % in January to 44.44 % in April.

The performance of a power plant can be known from the calculation of efficiency in the generating sector. Steam power plants utilize a series of energy conversion processes including: conversion of chemical energy into thermal energy when extracting heat from coal as fuel to heat boilers, conversion of thermal energy into mechanical energy in turbines and conversion of mechanical energy into electrical energy in generators. Like other steam power plants, the Teluk Sirih PLTU located in Bungus Teluk Kabung, West Sumatra has the same energy production process. it's just that the source of the water is taken from the sea so it requires special treatment to turn the water into water suitable for producing steam used in this power plant. The electricity production process will be explained in this study and an efficiency calculation process with a simple Rankine cycle is carried out to determine the efficiency of this power plant. From the calculation results, the thermal efficiency of PLTU Teluk Sirih is 29%. Based on the results of these calculations, it is known that the Telusk Sirih PLTU can be classified as a power plant with good efficiency.

Facing the future, whether working alone or with electric motors, a new type of variable compression ratio (VCR) engine that can achieve a high thermal efficiency under heavy load conditions is necessary. Hence, we propose a dual shaft control variable compression ratio (DSC-VCR) engine based on a gear-driven eccentric sleeve. With the improved position of gears, DSC-VCR allows for double larger gears to share the load, and the engine can operate with a larger eccentric size and a narrower adjustment range compared to other similar mechanisms. This helps to reduce the difficulty of chamber shape design, avoid collisions between valves and piston, and above all, makes the engine operate with a larger overexpansion ratio (OER, the ratio of expansion stroke and compression stroke) under all conditions to improve engine efficiency. Based on a 1.5 T four-cylinder engine, the OER can be increased to over 1.16 with the eccentric size of 6.5 mm. According to the theoretical thermal efficiency calculation while considering turbocharging, the per millimeter increase of eccentric size improves the theoretical efficiency by 0.0025–0.006. The predictive simulation presented that the reduction of residual gas helps to increase the compression ratio (CR) from 9.5 to 10.1 under a full load condition. Larger OERs and CRs help to reduce brake specific fuel consumption (BSFC) by 6%–8%. In the case of a 75% load, about 3.51% of efficiency increase was realized. All of these prove that DSC-VCR is a high-efficiency potential mechanism for the future.

Over the last few years, countries such as Brazil, the United States, Germany, and China have been receiving significant investments to advance the use of renewable energy sources, such as solar energy, biomass and wind. This has been due to the growing demand for electricity due to population increase and the evolution of industrial activities. Solar energy can be enjoyed by using solar concentrators that are commonly used in solar thermal systems where the working fluid reaches higher temperatures than can be obtained from other collectors. These concentrators are responsible for providing the thermal energy supply. This research analyzed the energy influence of Parabolic Solar Concentrator technology aided by a solar tracking system, taking into account its energy balance and thermal efficiency calculation. The concentrator had an optical efficiency of 81 % and was able to achieve average thermal efficiency values between 21.8 % and 24.7 % under maximum solar radiation conditions between 900 W/m² and 990 W/m². The temperature of the absorber tube used to receive the concentration of sunlight reached temperatures between 80 °C and 98.6 °C, allowing the system working fluid a temperature to reach values above 100 °C. These results show the ability of this type of solar collector to provide power for thermal applications such as heating water for industrial or domestic processes, food dehydration, and drying, refrigeration, thermal desalination and microgeneration of electricity. Besides, the thermal efficiency (between 21.8 % and 24.7 %) was satisfactory when considering the type of concentrator, which also validates the electronic tracking system as it was able to track the relative movement of the sun and favor the increase of thermal efficiency of the system.

Online simplified model and experimental comparison of CFB boiler thermal efficiency

This paper combines the wireless NB-IoT technology with the traditional boiler thermal efficiency test, and uses LabVIEW to develop a test analysis system. By installing the data export module and the transmission module together on the existing equipment to perform wireless and digital upgrade of the detection equipment, the purpose of improving the automation degree of the thermal efficiency test is achieved, thereby reducing the number of test staff on site. At the same time, it will avoid the dust and high temperature danger that the staff will encounter on site. The complex boiler thermal efficiency calculation formula is simplified according to the wireless, real-time and accurate needs of the boiler thermal efficiency test. A formula for calculating the enthalpy value that satisfies the requirements of online testing, a formula for the heat loss of the incomplete combustion of the gas, and a formula for fitting the ash combustibles are proposed.

This work presents the development of a virtual instrument for the acquisition of temperature data of a 3500 cc diesel engine and the calculation of its thermal efficiency at three different speeds, the analysis was made according to the standard cold air parameters for a diesel engine. To measure the temperature, type K thermocouples distributed around the combustion chamber and the engine exhaust was used; the data acquisition was carried out through a cDAQ-9178 and a NI-9213 thermocouple module from National Instruments.

In order to study the heat exchanger simulation and recovery device design of waste heat boiler of gas turbine generator set on Ocean platform, the theory of thermal cycle of gas turbine and the principle of steam turbine are introduced. The waste heat of exhaust gas of a certain type of gas turbine generator set on Ocean platform is taken as the object, to design the waste heat recovery device of this type of gas turbine generator set. According to the characteristics of the selected waste heat boiler, the mathematical model is reasonably simplified, and the steady-state simulation model of the waste heat boiler is established by using the computer simulation software, thus forming the whole model of the waste heat boiler. It is attempted to recover the waste heat from the exhaust gas of gas turbine generator set in Ocean platform by using gas-steam combined cycle power generation, which has certain reference significance for the design, application and improvement of a common gas turbine waste heat recovery device on Ocean platform. The established steady-state model simulation model and thermal efficiency calculation model have good accuracy, and have a certain auxiliary role in design calculation and performance research.

For the boiler main operation parameters, the deviation of operating parameters from the target value can cause the decrease of boiler thermal efficiency, which can further lead to the increase of unit coal consumption for power generation. Aimed at this problem, the key points of the thermal efficiency calculation for boilers mixedly burning pulverized coal and blast furnace gas (BFG) were analyzed, and the coal consumption deviation analysis model was proposed based on the modified calculation formulas. This model can provide further guidance for bolier optimized operation. A 220t/h boiler was analysed as an example, which the extra coal consumption was obtained caused by the non-optimal operation parameters.

Emissions from a domestic two-stage wood-fired hydronic heater: Effects of non-homogeneous fuel decomposition

Artificially roughness is one of the well known methods of enhancing heat transfer from the heat transfer surface in the form of repeated ribs, grooves or combination of ribs and groove (compound turbulators). The artificial roughness produced on the heat transferring surface is used in cooling of gas turbine blades, nuclear reactor, solar air heating systems etc. Solar air heaters have wide applications in low to moderate temperature range, namely, drying of foods, agricultural crops, seasoning of wood and space heating etc. Solar air heaters have low value of convective heat transfer coefficient between the working fluid (air) and the heat transferring surface, due to the formation of thin laminar viscous sub-layer on its surface. The heat transfer from the surface can be increased by breaking this laminar viscous sub layer. Hence, in the present work compound turbulators in the form of integral wedge shaped ribs with grooves are used on the heat transfer surface, to study its effect on the heat transfer coefficient (Nusselt number) and friction factor in the range of Reynolds number 3,000–18,000. The roughness produced on the absorber plate forms the wetted side of upper broad wall of the rectangular duct of solar air heater. The relative groove position (g/p) was varied from 0.4 to 0.8 and the wedge angle (Φ) was varied from 10° to 25°, relative roughness pitch (p/e) and relative roughness height (e/D) was maintained as 8.0 and 0.033 respectively. The aspect ratio of the rectangular duct was maintained as 8. The Nusselt number and friction factor of the artificially roughened ducts were determined experimentally and the corresponding values were compared with that of smooth surface duct. It is observed that wedge-groove roughened surface shows more enhancement in heat transfer compared to only rib roughened surface arrangement. The investigation revealed that Nusselt number increases 1.5–3 times, while the friction factor increases two to three folds that of the smooth surface duct in the range of operating parameters. It is also observed that in rib–groove roughness arrangement with relative groove position of 0.65 shows the maximum enhancement in the heat transfer compared to the other rib-groove roughness arrangements. Statistical correlations for the Nusselt number and friction factor have been developed by the regression method in terms of the operating and roughness parameters. A program was also developed in MATLAB for the calculation of thermal efficiency and thermal effectiveness. It was observed that the thermal efficiency is more for wedge angle of 15° and relative groove position of 0.65 and its value ranges from 42 to 73 %. The uncertainties in the measurements due to various instruments for the Reynolds number, Nusselt number, and friction factor have been estimated as ±3.8, ±4.54 and ±7.6 % respectively in the range of investigation made.

Monitoring of Mirror and Sensor Soiling with TraCS for Improved Quality of Ground based Irradiance Measurements

Thermal Efficiency Calculation of Composite Air-cooling System in Variable Conditions

In all industries which are related to heat, suitable thermal ranges are defined for each device to operate well. Consideration of these limits requires a thermal control unit beside the main system. The Satellite Thermal Control Unit (STCU) exploits from different methods and facilities individually or mixed. The space radiating fin which is combined with a heat pipe can be used to transfer the excess heat from the satellite to outer free space. The finite volume method is employed to simulate numerically the temperature distribution in a space radiating fin and evaluate thermal fin efficiency. Final results are achieved for two different materials (Aluminum and Beryllium) and compared to each other. The present results are compared with the other analytical methods and good agreement is shown.

We had proposed the noble hybrid cycle with epoch-making high efficiency and CO_2 recovery capability. In former study, we designed the 300MW plant conceptually, and the result shows that the efficiency of this system can reach 70% (HHV). However, in order to realize this system, huge MCFC manufacturing facilities are necessary. So, a smaller capacity plant should be developed first. Then we performed the examination on 1MW class unit that can be achieved in the near future. The thermal efficiency calculation result shows that the efficiency of this system is over 50% even with this smaller capacity.

A new method has been developed for simulation of heat regenerators in periodic operation. The procedure is based on describing the system by a number of backmixed cells in series, in contrast to the differential equation formulation used in earlier studies. The method is highly efficient computationally and the calculation of thermal efficiency and temperature profiles in the system is reduced to the solution of a simple set of linear algebraic equations. The validity of the method is established by comparing it with other solution procedures. Finally, some illustrative results are presented to show the effect of switching time, normalized variance of the system, and mode of operation.

ガラス管内に平らな集熱板を持ち, ガラス管の下に白色乱反射板を取付けた真空ガラス管型集熱器に関して, 有効透過吸収係数 (τα) eの太陽光入射方向依存性を考慮して, 瞬時集熱効率を計算する方法を導いた.理論計算による集熱効率特性と実測によるそれとはほぼ同じ傾きを持ち, 集熱器からの熱損失に関する理論計算の正しさが証明された.理論計算された集熱効率ηthと実測された集熱効率ηmは太陽光の入射方向の変化に関してほぼ同じ傾向を持ち, 理論計算式から算出された (τα) eの入射方向依存性も実際の集熱器のそれとほぼ一致することが示された.