Average Working Temperature Research Articles

Direct coupling of pressurized gas receiver to a brayton supercritical CO2 power cycle in solar thermal power plants

Three layouts of Brayton supercritical CO2 power cycles directly coupled to the receiver are proposed for Generation 3 solar power plants: conventional recompression, recompression with partial cooling, and recompression with intercooling. To achieve direct coupling, the solar heat is introduced downstream of the turbine, where CO2 pressure is lower. A higher temperature rise diminishes the receiver's dimensions, thus increasing its energy efficiency. It also lowers the average working temperature since the maximum temperature is fixed at 700 °C, thereby reducing losses. However, optical efficiency decreases as the receiver size diminishes. Both intercooling and partial cooling layouts further increase the cycle's net efficiency, which reduces the receiver's size, following similar trends observed with an increase in temperature rise. Considering all these effects, various factors push in opposite directions, affecting overall efficiency and costs. This competitive interplay results in overall efficiencies ranging from 30.26 % to 31.58 % and Levelized Costs of Electricity (LCOEs) between 162.47 €/MWh and 166.81 €/MWh. In conclusion, similar outcomes in terms of energy and economics are achieved with the three layouts, suggesting the simplest layout (recompression) as the most advisable. If thermal storage is incorporated, partial cooling becomes preferable due to its significant increase in the receiver's temperature rise.

Energy conservation: Virtual energy audit of an industrial plant

Energy consumed by manufacturing industries constitutes a large part of the total energy consumption of the world. In India, almost 50% of the total energy consumption is done by Industries. Energy bills are usually a major contributor to the operating expenses of a company. Industries can profit from the opportunities coming out of energy saving by the implementation of effective energy management using appropriate tools. An industrial plant layout is usually designed within several constraints, mainly operational. The objectives were decided by the company to study and identify energy gaps in the industrial plant and suggest suitable solutions to reduce energy consumption all while reducing the average working temperature inside the plant from 38 °C to an ideal value below 30 °C, preferably without installing an air conditioning system. The study was divided into two parts; Primarily, Data collection and observations of the plant operations and then Building Energy Modelling and simulation. The base model with existing conditions was modelled, simulated and validated with historical energy consumption data and temperature readings taken inside the plant.The proposed solutions include limited modifications in the existing set up considering the operational constraints. The simulations run with proposed modifications indicate a maximum of 11 % savings in energy consumed by lighting and potential to reduce temperature to 33.23 °C from 38 °C. The effect of ambient factors according to the geographical location such as sun exposure, wind directions, humidity were also taken into consideration.

Perbandingan Penggunaan Cairan Pendingin Radiator Terhadap Temperatur Kerja Mesin Mobil Toyota Avanza 1.5 S M/T

The increasing economic growth of the Indonesian people has implications for the number of vehicle ownership, especially cars. However, this increase is not matched by public understanding of the need for maintenance of the engine cooling system. One way that can be done is to use radiator coolant to maintain the cooling system so that engine performance remains in optimal condition. The purpose of this study was to determine and compare the working temperature of the engine when using several types of radiator coolant. This research uses an experimental approach research method. The test was carried out at 750 RPM, 1500 RPM, 3000 RPM and using a coolant containing a mixture of water with ethylene glycol 0%, 30%, 50% and 80%. In the calculation, it is found that the working temperature of the Toyota Avanza 1.5 M/T car engine is very good using a mixture of water and ethylene glycol 50%, namely with an average engine working temperature of 94.8℃, then a mixture of water and ethylene glycol 30%, namely with an average temperature engine working 96.3℃, a mixture of water and ethylene glycol 80%, with an average working temperature of 98.6℃ engine and a mixture of water and ethylene glycol 0%, with an average working temperature of 101.5℃

Uninterrupted Self‐Generation Thermoelectric Power Device Based on the Radiative Cooling Emitter and Solar Selective Absorber

Self‐generation power devices based on the radiative cooling effect have intense potential applications in the energy conversion field. A selective solar absorber is introduced into thermoelectric generator (TEG) devices based on radiative cooling emitters (RCEs). The self‐generation device can work continuously for 24 h, and the output power is greatly enhanced. The RCE is prepared as a polydimethylsiloxane–Al structure by a simple squeegee method. The solar selective absorber (SSA) of the W–Si–O laminated film is prepared by the magnetron sputtering method. Its working temperature can reach as high as 85 °C under AM1.5 sunlight. The calculation results prove that the selective solar absorber can achieve 1.55 times the net heating power of an ideal blackbody at the same working temperature of 85 °C. The assembled self‐generation power device achieves output powers of 695.1 and 5.23 mW m−2 on clear days and nights, respectively, as well as an output power of 7.64 mW m−2 even in the cloudy daytime. The result of theoretical calculation proves that the addition of SSA can greatly increase the temperature difference and the average working temperature, which improves the efficiency of the TEG and the output power of the device.

Response Times of Metal-Oxide Chemiresistors: Comparison Between the Isothermal and Temperature Modulation Modes.

The response time is one of the main functional parameter for gas sensors, including metal oxide chemiresistors. This parameter is widely investigated for devices working in isothermal mode but it is much less investigated for gas sensors working in temperature modulation mode. In this work, considering ethanol as target gas, we compare the response times of a metal oxide chemiresistor working according to these two modes. In order to compare them, we worked with nearly the same average temperature in both cases, supplying a constant voltage to the heater in the isothermal mode and a squared voltage wave in temperature modulation. Our results show that, depending on the average working temperature, one mode or the other may be faster. At high average working temperature, the response time recorded with the isothermal mode is shorter than the thermal-period of the temperature modulation mode. Lowering the average working temperature, the response time increases for both modes, but the increase is more marked for the isothermal mode, which become slower than the temperature modulation one.

Photovoltaic Performance with Heat Sink from Copper and Aluminum Material

Energy becomes a basic human need, so energy reserves are needed. Solar energy is the solution to overcome this problem. Solar energy can be converted into electrical energy through PV panels. However, high temperatures can make PV panels do not work optimally. One way to reduce the temperature is to use a heat sink. The materials used are PV panels without heat sinks, PV panels with aluminum heat sinks, and PV panels with copper heat sinks. This research shows that with the same intensity of 1100 W/m2 PV panels without heat sinks, PV panels with aluminum heat sinks and PV panels with copper heat sinks have an efficiency of 8.76%, 10.27% and 11.14%. The result of temperatures 69.7 °C, 60.8 °C and 52.7 °C and the maximum power produced is 35.19 W, 40.17 W and 43.58 W. The results showed that the average working temperature decreased 8.9 °C and 17 °C, thereby increasing output power by 4.98 W and 8.39 W and increasing efficiency by 1.51% and 2.38% without using a heat sink.

Biogas production from blends of fonio husk and donkey dung via anaerobic digestion for sustainable development

There is growing public concern over potential impact on environmental quality caused by animal wastes. Anaerobic digestion, a biological conversion process can be used to obtain energy from biologicall wastes. This study explored the production of biogas from co-digestion of fonio hus and donkey dung using anaerobic biological conversion. The digesters were labeled as; digester A –Fonio husk only, digester B - donkey dung only, digester C – Fonio husk (300g) and Donkey Dung (200g), digester D – Fonio husk (200g) and donkey dung (300g). Proximate analysis of the substrates before and after digestion were determined such as total solids (TS), volatile solid, carbon content, nitrogen content, ash content, etc., and pH before and after digestion process. The biogas produced during this period was collected by water displacement method and subsequently measured. The results showed that Fonio husk in bio-digesters A and B gave a cumulative average biogas volume of 4972 ml and 5222 ml (week 3) while pig dung in bio-digesters C and D gave a cumulative average biogas volume of 5564 ml and 5978 respectively (week 3) within three weeks of fermentation. The digester is capable of producing 0.007m at average working temperature of 320C. Digester D produces higher volume of biogas as a result of improved nutrient provide by donkey dung as shown in the results obtained from the proximate analysis and has the best neutral pH, there was a reduction in the startup time. Â

Performance analysis of an improved 30 MW parabolic trough solar thermal power plant

As a promising application of solar energy, parabolic trough solar thermal power generation technology is one of the most important methods of solar thermal utilization. This paper takes the SEGS VI parabolic trough plant as the research object and proposes an improved 30 MW parabolic trough solar thermal power plant. An optimization model is established for the overall plant efficiency, and the design of the solar field of the improved plant is presented with an explanation in this paper. This paper uses the commercial software Ebsilon to establish the simulation models of the SEGS VI Plant and the improved plant and conducts a performance analysis of the two plants under design and operating conditions. The results show that the improved plant based on sectional heating can reduce the average working temperature of the thermal oil. The solar field efficiency increases by 0.52% and the overall plant efficiency increases by 0.24% under the design conditions. The daily mean solar field efficiency data increase by 0.53%, and the overall plant efficiency increases by 0.22% under operating conditions. Simultaneously, the number of collectors in the solar field also decreases, which has good application prospects.

Electrical contact performance of various electro-deposited graphene reinforced silver-based nanocomposites

Abstract Silver and silver(Ag)-graphene(Gr) nanocomposite coatings were prepared via direct current, pulse current and pulse reverse current on copper electrical contacts for evaluating electrical contact performance. The effects of the addition of Gr and current types on microstructure, crystallographic orientation, mechanical properties and electrical contact performance were investigataed via a scanning electron microscope, an X-Ray diffractometer, microhardness test device and an electrical contact test device, respectively. The addition of Gr changed the Ag surface morphology and decreased grain sizes. Moreover, the addition of Gr significantly improved arc erosion resistivity and decreased the average working temperature during the contact test. In addition, pulse current and pulse reverse current provided a significant improvement in microhardness and electrical contact erosion resistance owing to increased embedded graphene amounts in silver layers.

Electrical contact performance of various electro-deposited graphene reinforced silver-based nanocomposites

Abstract Silver and silver(Ag)-graphene(Gr) nanocomposite coatings were prepared via direct current, pulse current and pulse reverse current on copper electrical contacts for evaluating electrical contact performance. The effects of the addition of Gr and current types on microstructure, crystallographic orientation, mechanical properties and electrical contact performance were investigataed via a scanning electron microscope, an X-Ray diffractometer, microhardness test device and an electrical contact test device, respectively. The addition of Gr changed the Ag surface morphology and decreased grain sizes. Moreover, the addition of Gr significantly improved arc erosion resistivity and decreased the average working temperature during the contact test. In addition, pulse current and pulse reverse current provided a significant improvement in microhardness and electrical contact erosion resistance owing to increased embedded graphene amounts in silver layers.

Comparative Study of Biogas Production from Anaerobic Co-digestion of Donkey Dung and Swine Dung

Production of sufficient sustainable sources of energy, mitigation of green house gas emissions amongst others are the aspiring goals that have led in developing technologies to produce more energy from renewable sources. This study investigated the potentials of an alternative fuel sources for biogas production, it was carried out using donkey dung and swine dung as substrates, further co-digestion of both donkey dung and swine dung was done to differentiate between independent and co-digestion of substrates. Digesters were used to digest swine dung and donkey dung respectively as single substrates as well as to co-digest swine dung and donkey dung. The operating conditions here are pH value 7.2, Temperature 32°C and retention time of 68 days. Effect of seeding with bacteria increases the rate of production and mixing is an essential part that also aids the production of biogas. This work presents the design and construction of biogas digester to treat 500g of swine dung and donkey dung. The digester is capable of producing 0.007m at average working temperature of 32°C. Digester D produces higher volume of biogas. Therefore, from the values of the physic-chemical properties with the sufficient carbon obtained, it will increase the sufficient effective biogas production as an alternative source of energy.

Study on thermal field coupling simulation of methane sensor based on ceramic micro-hot plate

In view of the lack of high concentration online gas detection sensors in the current mine safety monitoring system to cope with gas emission and gas outburst, a design method of full-range gas sensor based on ceramic micro-hot plate is presented in this paper. COMSOL finite element simulation is used to study the thermal field coupling of sensor array units. Based on the electro-thermal coupling model, the thermal field was est ablished, and the influence of isolation groove, base material, working temperature and platinum film thickness on the thermal interference between the sensor units was studied. The results show that the heat loss is reduced by 2.57 times and the heating efficiency is improved. Compared with AlN and SiC ceramic substrates, Al2O3 has the least thermal disturbance and the best thermal performance. The average working temperature at 1.3v reaches 587.77k. The temperature difference between the units is directly proportional to the unit operating temperature. Increasing the thickness of platinum film can improve the working temperature and heating efficiency. The research provides a t heoretical basis for the design of the integrated MEMS array gas sensor.

Influence of Ambient Temperature, Wind Speed, Emissivity, and Average Working Temperature of Light-Absorbing Heat-Exchange Panels of Flat-Plate Solar Water-Heating Collectors on Their Thermal Losses Through Translucent Coatings

This article presents the results of computational experiments aimed at determining the influence of the ambient temperature ( $${{t}_{a}}$$ ), wind speed (v), average working temperature ( $${{\bar {t}}_{{avw}}}$$ ), and emissivity of light-absorbing heat-exchange panels (LAHPs) $$\left( {{{\varepsilon }_{p}}} \right)$$ on their thermal losses through the translucent coating (TC) of the case of flat-plate solar water heating collectors (FSWHC) with a single-layer TC.

Temperature distribution analysis of different technologies of PV modules using infrared thermography

Photovoltaic systems are designed to operate for a very long time according to the modules’ warranty that guarantees at least of 80% of the nominal power production after 20 years of use. In order to assure the continuous power production with a high level for a long time, thermographic analysis should be performed to detect incipient anomalies in individual modules and junction boxes. This safe, convenient and noncontact method allows carrying out the inspection for working system without any contact with live wiring and without disconnecting the PV systems. Temperature distribution of the module surface can reveal many different types of anomalies, i.e. hot spots caused by local shading, microcracking or cell breakage. This paper shows the results of the infrared thermography analysis of the operating PV systems consisting of different technological modules: polycrystalline silicon (pc-Si), copper indium gallium diselenide (CIGS) and cadmium telluride (CdTe). The average working temperature of each different kind of technological module as well as overheated areas were investigated in this study. Temperature of the MC4 connectors was also analysed.

Virtual method for the determination of an optimum thermal design of hot stamping tools

This work presents a new virtual method for the optimised thermal design of hot stamping tools. It provides optimal positions of the tool's tempering ducts with respect to the average working temperature and its homogeneous distribution on the surface of a tool. It consists of a specific procedure for hot stamping tool design and a software framework in order to interconnect three domains: (I) a parametrised CAD tool model, (II) a linear thermal solver using a fast boundary element method and (III) an optimisation algorithm. This enables the automated set-up, simulation and optimisation of a duct topology. The boundary conditions for the simulations are derived from a reduced model of the thermal loading of the tool. The virtual method proposed is demonstrated on simplified tool segment geometries. The results are transferred to complex tool designs used in industry. For a selected use case, the number of ducts could be reduced by 50% through the application of the proposed method. These results are validated virtually based on an existing design. Hence, the new virtual method contributes to a CAE-driven tool design and a more efficient tool manufacturing.

A simple method to characterize the impedance of pyroelectric materials at ultra-low frequencies

The purpose of this work is to demonstrate a new simple stand-alone method of characterizing the impedance of a pyroelectric cell. This method utilizes a pyroelectric single pole low-pass filter technique. Utilizing the properties of a pyroelectric single pole low-pass filter technique, a known input voltage is applied and using simple equations, capacitance Cp and resistance Rp at a frequency range of 1 mHz to 1 Hz can be calculated. For verification purposes, an LCR meter and an impedance analyzer were exploited at 10 and 100 Hz, respectively. Results showed that Rp values for two materials, lead zirconate titanate-5A and polyvinylidene difluoride, were within 8%, and Cp values were within 7.5%. In addition, to verify the importance of the impedance values in energy harvesting applications, output power was measured with varying impedance values. The optimal load resistances for polyvinylidene difluoride and lead zirconate titanate-5A were consistent with the measured pyroelectric impedance at the particular heat range with 10.9% and 1.4%, respectively. The pyroelectric single pole low-pass filter method presented here demonstrates that for pyroelectric materials the impedance depends on two major factors: (1) average working temperature and (2) the heating rate. Neglecting these two factors can result in inefficient and unpredictable behavior of pyroelectric materials when used in energy harvesting applications.

Performance evaluation of controllable separate heat pipes

A controllable separate heat pipe (CSHP) combined with cool storage can be an efficient and low-cost solution to release the necessary cool power and to improve the precision in the temperature control of cool-storage refrigerators powered by solar energy or electricity with time-of-use price policy. However, the precise temperature control performance of separate heat pipes under active control depends on system design and thus should be confirmed. In this study, a CSHP was developed and an active control method was achieved by interrupting its two-phase natural circulation flow. A one-dimensional steady-state model was used to calculate the critical fill ratio, heat transfer rate, and average working temperature of CSHP. A series of experiments was conducted to analyze the start–stop and heat transfer performances of CSHP at various R134a fill ratios and heat sink temperatures. Under different test conditions, the optimum working points were obtained through fitting. The most suitable control mode was determined and the start–stop performance of CSHP was examined in detail. CSHP starts up quickly in approximately 15 seconds and the quickest stopping time of CSHP approximates to 80 seconds. Therefore, the performance of CSHP under active control can be applied to cool-storage refrigerators.

THE THERMAL MODEL OF A FLAT-PLATE SOLAR WATER-HEATING COLLECTOR

The paper offers a thermal model to determine the specific heat productivity of flat-plate solar water-heating collector (FSWHC) depending of the pre-assigned temperature values of obtaining hot water. Unlike existing thermal models of FSWHC, for the first time in the proposed model the research results obtained by the authors are used to determine the average mass temperature of the heat-transfer (water) collectors, heat efficiency coefficient and the surface average working temperature of the light-absorbing heat-exchange panels (LAHP) by non-contact method, depending of the effective coefficient of LAHP heat losses. In order to determine the coefficient we have to take into account the partial absorption influence and conversion into heat of the total solar radiation passing through translucent cover of collector case and also the value of the LAHP surface average working and ambient temperature. It is provided a practical example of realization and proved authenticity of the model.

Energy Efficiency Versus Reliability Performance in Optical Backbone Networks [Invited

Improving the energy efficiency in telecommunication networks has been one of the main research topics of the past few years. As a result, many energy efficient algorithms have been proposed, some focusing on maximizing only the energy savings, others considering also the impact that green strategies have on other network performance metrics, e.g., delay, utilization of network resources, and blocking probability. The aim of this paper is to provide new insight on the impact of energy efficient strategies, i.e., investigating the trade-off between green network operations and the reliability performance of optical backbone devices. The study is motivated by the intuition that energy efficient strategies are usually based on putting unutilized devices in power saving (sleep) mode, which can have some side effects (e.g., frequent on/sleep switching, and/or high fiber link utilization) that may affect the working conditions of a device. To better understand these phenomena, this paper presents a number of models aimed at estimating the reliability performance changes of a device as a function of its average working temperature, of its temperature variations, and of its average occupancy. These models are then used to carry out a study both at the component and at the network levels. The study at the component level shows that erbium-doped fiber amplifiers (EDFAs) are critical devices, i.e., their achievable energy savings might not cover the additional reparation costs resulting from their reliability performance degradation. Similar findings are reached also with the network level study. In summary, it can be concluded that the use of energy efficient routing algorithms based on setting EDFAs in sleep mode may not always be beneficial.

Analysis of low temperature solar thermal electric generation using regenerative Organic Rankine Cycle

The innovative configuration of low temperature solar thermal electric generation with regenerative Organic Rankine Cycle (ORC) is designed, mainly consisting of small concentration ratio compound parabolic concentrators (CPC) and the regenerative ORC. Advantages of the innovative configuration such as effectively reducing heat transfer irreversibility and permitting the use of thermal storage with phase change materials (PCMs) are outlined. The numerical simulation of the heat transfer and power conversion processes are carried out based on distributed parameters. The effects of regenerative cycle on the collector, ORC, and overall electricity efficiency are then analyzed. The results indicate that the regenerative cycle has positive effects on the ORC efficiency but negative ones on the collector efficiency due to increment of the average working temperature of the first-stage collectors. Thus, it is necessary to evaluate the overall electricity efficiency when regenerative cycle is adopted. Further investigation shows that there are maximum efficiencies for both the ORC and the system electric generation on conditions of constant irradiance, evaporation temperature, and environment temperature. And the regenerative temperature at which the system electricity efficiency reaches its maximum is smaller than that at which the ORC efficiency reaches its maximum by 12–21 °C. Thus, the regenerative cycle optimization of the solar thermal electric generation differs from that of a solo ORC. The system electricity efficiency with regenerative ORC is about 8.6% for irradiance 750 W/m2 and is relatively higher than that without the regenerative cycle by 4.9%.