Hybrid thermal-photovoltaics water distillation equipment design and its thermodynamic analysis

Thermodynamic analysis of the cascaded packed bed cryogenic storage based supercritical air energy storage system

Low- and high-temperature oxidation processes, including thermal auto-ignition under diesel-engine-like conditions (non-premixed mixtures), have been investigated. A special combustion chamber, characterized by constant volume and adiabatic conditions, has been used as an engine simulator. The investigated processes are very complex in nature, and depend significantly on the temperature and pressure. There are five characteristic regions of the process characterized by different delay times, reaction rates and number of recognizable oxidation reactions: region 1 corresponds to processes occurring at low initial pressures over a wide range of initial temperatures; region 2 corresponds to low initial temperatures over a wide range of initial pressures; region 3 corresponds to middle pressures and higher temperatures; region 4 corresponds to middle temperatures and higher pressures; and region 5 corresponds to high initial pressures and high temperatures. by analogy to a negative temperature coefficient (as discussed in the literature), a positive pressure coefficient has been introduced here. This indicates that in the selected range of pressures, the delay time of low-temperature oxidation processes is the shortest, and the rate of these reactions is the highest. Further increases in the pressure behind the positive pressure coefficient range increase the delay time and decrease the reaction rate. The positive pressure coefficient has been observed at lower temperatures (mostly corresponding to cool-flame reactions and transitions to blue flames). Generally, the ignition delay time reduces with increasing chamber temperature and pressure.

Thermal design of heat-exchangeable reactors using a dry-sorbent CO2 capture multi-step process

Thermodynamic analysis and optimization of densely-packed receiver assembly components in high-concentration CPVT solar collectors

The relationship between body temperature and the hunting response (intermittent supply of warm blood to cold exposed extremities) was quantified for nine subjects by immersing one hand in 8 degree C water while their body was either warm, cool or comfortable. Core and skin temperatures were manipulated by exposing the subjects to different ambient temperatures (30, 22, or 15 degrees C), by adjusting their clothing insulation (moderate, light, or none), and by drinking beverages at different temperatures (43, 37 and 0 degrees C). The middle finger temperature (Tfi) response was recorded, together with ear canal (Tear), rectal (Tre), and mean skin temperature (Tsk). The induced mean Tear changes were -0.34 (0.08) and +0.29 (0.03) degrees C following consumption of the cold and hot beverage, respectively. Tsk ranged from 26.7 to 34.5 degrees C during the tests. In the warm environment after a hot drink, the initial finger temperature (T(fi,base)) was 35.3 (0.4) degrees C, the minimum finger temperature during immersion (T(fi,min)) was 11.3 (0.5) degrees C, and 2.6 (0.4) hunting waves occurred in the 30-min immersion period. In the neutral condition (thermoneutral room and beverage) T(fi,base) was 32.1 (1.0) degrees C, T(fi,min) was 9.6 (0.3) degrees C, and 1.6 (0.2) waves occurred. In the cold environment after a cold drink, these values were 19.3 (0.9) degrees C, 8.7 (0.2) degrees C, and 0.8 (0.2) waves, respectively. A colder body induced a decrease in the magnitude and frequency of the hunting response. The total heat transferred from the hand to the water, as estimated by the area under the middle finger temperature curve, was also dependent upon the induced increase or decrease in Tear and Tsk. We conclude that the characteristics of the hunting temperature response curve of the finger are in part determined by core temperature and Tsk. Both T(fi,min) and the maximal finger temperature during immersion were higher when the core temperature was elevated; Tsk seemed to be an important determinant of the onset time of the cold-induced vasodilation response.

Thermodynamic analysis and performance of an adsorption refrigeration system driven by solar collector

Thermodynamic analysis of a sustainable hybrid dryer

In this paper, two OLED device concepts are introduced. First, classical phosphorescent green carbene emitters with unsurpassed lifetime, combined with low voltage and high efficiency are presented and the associated optimized OLED stacks are explained. Second, a path towards highly efficient, long-lived deep blue systems is shown. The high efficiencies can be reached by having the charge-recombination on the phosphorescent carbene emitter while at the same time short emissive lifetimes are realized by fast energy transfer to the fluorescent emitter, which eventually allows for higher OLED stability in the deep blue. Device architectures, materials and performance data are presented showing that carbene type emitters have the potential to outperform established phosphorescent green emitters both in terms of lifetime and efficiency. The specific class of green emitters under investigation shows distinctly larger electron affinities (2.1 to 2.5 eV) and ionization potentials (5.6 to 5.8 eV) as compared to the "standard" emitter Ir(ppy)₃ (5.0/1.6 eV). This difference in energy levels requires an adopted OLED design, in particular with respect to emitter hosts and blocking layers. Consequently, in the diode setup presented here, the emitter species is electron transporting or electron trapping. For said green carbene emitters, the typical peak wavelength is 525 nm yielding CIE color coordinates of (x = 0.33, y = 0.62). Device data of green OLEDs are shown with EQEs of 26 %. Driving voltage at 1000 cd/m² is below 3 V. In an optimized stack, a device lifetime of LT₉₅ > 15,000 h (1000 cd/m²) has been reached, thus fulfilling AMOLED display requirements.

A mathematical model was developed for the flat plate solar collector with variable solar radiation. In this study, the governing equations were derived applying the energy balance for each control volume of the solar collector and the storage tank. The solar thermal collector was divided into five nodes, namely glass cover, air gap, absorber, working fluid, and insulation. For each node, the discretization equations were derived applying the control volume method. The forward and backward finite difference method was employed to solve the system of nonlinear equations. The time derivatives were replaced by a forward difference scheme, whereas the dimensional derivatives were replaced by a backward difference scheme. In this work, the influence of different types of parameters such as the number of nodes, flow rates, time intervals, initial temperature and the amount of working fluid was studied to optimize the performance of the flat plate solar collector especially suitable for the climatic condition of Bangladesh. The software package MATLAB version R2015a was used for coding and the derived results were shown graphically. Flat plate solar collector operation with variable solar radiation may be designed using the proposed model that could be utilized for supplying hot water in the industrial and household works having a maximum temperature of 51℃ and thereby would help in conserving the fossil fuel/electricity maintaining harmony with the environment. The model may be used to predict the temperature of the working fluid that could be raised to its maximum level subject to the local ambient temperature and variable solar radiation.

An experimental study is carried out to investigate the heat transfer characteristics of silver/water nanofluid in a solar flatplate collector. The solar radiation heat flux varies between 800 W/m2and 1000W/m2, and the particle concentration varies between 0.01%, 0.03%, and 0.04%. The fluid Reynolds number varies from 5000 to 25000. The influence of radiation heat flux, mass flow rate of nanofluid, inlet temperature into the solar collector, and volume concentration of the particle on the convective heat transfer coefficient and the collector efficiency are studied. Both parameters increase with increase in the particle volume concentration and flow rate. The maximum percentage increase obtained in the convective heat transfer coefficient is 18.4% for the 0.04% volume concentration at a Reynolds number of 25000. An increase in the performance of nanofluid is also witnessed when compared to the base fluid, which has a strong dependency on volume concentration and mass flow rate. MgO. The nanofluid achieved a 3°C temperature difference during the daytime peak solar radiation compared with the base fluids. With a concentration of 0.2% ZnO, a temperature difference of 2.55°C for daytime and 1°C for nighttime was reached, and this was determined to be the most attractive option for solar energy utilization. Yousefi et al. [15] witnessed a 28% performance improvement in a flat-plate collector when it was operated with water-Al2O nanofluids. Tyagi [16] theoretically compared the conventional flat-plate collector with a direct absorption solar collector (DAC) and observed the former to be 10% more efficient. Otanicar [17] studied the conomic and environmental influences of using nanofluids to enhance solar collector efficiency with conventional solar collectors. Dongxiao et al. [18] presented excellent photothermal properties of carbon-black aqueous nanofluids at highvolume fractions. Further work on nanofluids’ application to direct solar absorption has been carried out by Lijuan Mu [19] using a custom-made direct solar absorber. The radiative properties of several nanofluids are tested for the highest temperature difference across the heat exchangers. Based on the above-mentioned review of the literature, it has been clearly observed that most of the previous studies on solar flat-plate collectors were conducted using metal oxide nanoparticles in relatively high concentrations. These high concentrations of metal oxide nanoparticles cause a higher pressure drop that then requires a higher pumping power. Since a limited number of studies exists in the literature with respect to pure metal nanoparticles, it is recommended to study the heat transfer characteristics of pure metal nanoparticles with relatively low concentrations (

This work presents performance analysis of a novel multi-pass solar air collector with perforated fins (MPSACF) in winter conditions, Ankara province, Turkey. The aim of this work is to experimentally test and compare the performance of the two different design of solar collectors in the same climatic conditions. In addition, a double-pass solar air collector without fins (DPSAC) at the same absorber area was manufactured and tested as a control group. The total absorber area of both solar collectors is 0.325 m2. Thermal effects for performance improvement of the collectors have been designated. Average thermal efficiency values of DPSAC and MPSACF were calculated as 47.85% and 51.86%, 67.10% and 72.86%, respectively in experiments performed at 0.0069 kg/s (0.7 m/s air velocity) and 0.0087 kg/s (0.9 m/s air velocity) mass flow rates. Exergy efficiency of DPSAC and MPSACF were 2.10-17.12% and 8.74-23.97%, respectively. Coefficient of performance(COP) values were ocomputed 4.63 and 4.94, 3.18 and 3.48 respectively in experiments performed at 0.0069 kg/s and 0.0087 kg/s mass flow rates. Although the MPSACF has high efficiency values, COP values are lower due to the presence of dual fans. Because of their high thermal efficiency, both collectors can be effectively practiced for applications such as preheating, space heating and ventilation, greenhouse heating and product drying©2019. CBIORE-IJRED. All rights reservedArticle History: Received May 16th 2018; Received in revised form October 16th 2018 ; Accepted January 6th 2019; Available onlineHow to Cite This Article: Aktaş, M., Sözen, A., Tuncer, A.D., Arslan, E., Koşan, M., Çürük, O. (2019) Energy-exergy analysis of a novel multi-pass solar air collector with perforated fins. International Journal of Renewable Energy Development, 8(1), 47-55.http://dx.doi.org/10.14710/ijred.8.1.47-55

Abstract. The paper presents the description and operating principle of energy-saving mini-grain dryers for drying small grain batches on farms using conductive and convective drying methods and the process of grain cooling with heat obtained from a traditional heat source and a heat carrier prepared with a solar collector or a charged heat storage. (Research purpose) To develop and study a compact energy-saving grain dryer, with a heat supply system based on both a traditional source and a heat transfer fluid heated by a solar collector or a charged heat storage. (Materials and methods) The authors have carried out experimental studies of the drying process of wheat grain to determine the effectiveness of the developed unit for grain drying; the main condition for saving energy has been taken as the minimization of the total unit cost of the evaporation of one kilogram of moisture. (Results and discussion) The authors have conducted a two-factor experiment to determine the main optimal parameters affecting the grain drying process - the speed of grain movement in the conductive chamber and the temperature of the heating surface of its casing based on the calculated mathematical model. In the first variant, the drying process was carried out only by the conductive method using the heat from a traditional energy source. In the second variant, the drying was carried out by successive use of conductive and convective methods, and the grain was cooled using both thermal energy received from a traditional source and solar radiation heat along with the heat of the spent heat carrier. (Conclusions) The study has revealed that the most effective option in terms of saving thermal energy is grain drying with the consistent use of conductive and convective drying methods followed by grain cooling. The heat supply of the drying unit was partially carried out by using the heat of solar radiation and the heat obtained from the spent coolant recycling. In this optimal variant, the heat consumption for evaporation of one kilogram of moisture from the grain is minimal and amounts to 1.53-2.50 MJ per kilogram with a grain movement speed of in the dryer of 0.007-0.011 m per second and a heating surface temperature of 85-91 degrees Celsius.

From Indian perspective there is a large potential available for low cost solar water heating systems. The described system can instantly fulfil needs of hot water in industrial sector. This type of system can be used for heating boiler feed water, laundry applications and other steam generation applications. In general, concentrated solar collectors have high efficiency as compared to flat plate and evacuated tube solar collectors. Therefore, for water heating application, high efficiency can be achieved. Authors used parabolic dish collector for instant water heating application. This paper reveals prototype design of solar parabolic dish collector with truncated cone shaped helical coiled receiver made up of copper and coated with nickel chrome at focal point. Instantaneous efficiency of 63.9% has been achieved with the system explained in this paper. This prototype has been evaluated for its performance during month of April and May 2010 at Shivaji University, Kolhapur, Maharashtra, India [Latitude: 16.42° North, Longitude: 74.13° West].

The Gas Technology Institute (GTI) has developed a pressurized oxy-coal fired molten bed boiler (MBB) concept, in which coal and oxygen are fired directly into a bed of molten coal slag through burners located on the bottom of the boiler and fired upward. Circulation of heat by the molten slag eliminates the need for a flue gas recirculation loop and provides excellent heat transfer to steam tubes in the boiler walls. Advantages of the MBB technology over other boilers include higher efficiency (from eliminating flue gas recirculation), a smaller and less expensive boiler, modular design leading to direct scalability, decreased fines carryover and handling costs, smaller exhaust duct size, and smaller emissions control equipment sizes. The objective of this project was to conduct techno-economic analyses and an engineering design of the MBB project and to support this work with thermodynamic analyses and oxy-coal burner testing. Techno-economic analyses of GTI’s pressurized oxy-coal fired MBB technology found that the overall plant with compressed CO2 has an efficiency of 31.6%. This is a significant increase over calculated 29.2% efficiency of first generation oxy-coal plants. Cost of electricity (COE) for the pressurized MBB supercritical steam power plant with CO2 capture and compression was calculatedmore » to be 134% of the COE for an air-coal supercritical steam power plant with no CO2 capture. This compares positively with a calculated COE for first generation oxy-coal supercritical steam power plants with CO2 capture and compression of 164%. The COE for the MBB power plant is found to meet the U.S. Department of Energy (DOE) target of 135%, before any plant optimization. The MBB power plant was also determined to be simpler than other oxy-coal power plants with a 17% lower capital cost. No other known combustion technology can produce higher efficiencies or lower COE when CO2 capture and compression are included. A thermodynamic enthalpy and exergy analysis found a number of modifications and adjustments that could provide higher efficiency and better use of available work. Conclusions from this analysis will help guide the analyses and CFD modeling in future process development. The MBB technology has the potential to be a disruptive technology that will enable coal combustion power plants to be built and operated in a cost effective way, cleanly with no carbon dioxide emissions. A large amount of work is needed to quantify and confirm the great promise of the MBB technology. A Phase 2 proposal was submitted to DOE and other sponsors to address the most critical MBB process technical gaps. The Phase 2 proposal was not accepted for current DOE support.« less

The structural relaxation process has been examined by a Monte Carlo simulation for a two‐dimensional XY clock model that has two transition points, a Kosterlitz‐Thouless transition at TKT and a long range order transtiion at TC (TC<TKT). The system was quenched from the middle temperature phase between TC and TKT to low temperature phase below TC. The structure relaxation rate at low temperature phase is slower for the initial middle temperature state that has been created directly from the high temperature phase above TKT than that created from the low temperature phase below TC, both middle temperature phases being kept for the time insufficient for equilibration.