首页期刊导航|Applied thermal engineering
期刊信息/Journal information
Applied thermal engineering
Elservier Science Ltd.
Applied thermal engineering

Elservier Science Ltd.

1359-4311

Applied thermal engineering/Journal Applied thermal engineeringISTPSCIEI
正式出版
收录年代

    Performance analysis and dynamic optimization of integrated cooling and power generation system based on supercritical CO_2 cycle for turbine-based combined cycle engine

    Yinhai ZhuXiaofeng MaPeixue Jiang
    15页
    查看更多>>摘要：Turbine-based combined cycle (TBCC) engines are the most promising propulsion systems for the horizontal takeoff and landing of hypersonic vehicles. However, the high air-inlet temperature, engine-wall temperature, and electrical-energy demand hinder the application of the system. In this study, a novel integrated cooling and power generation system based on a supercritical CO_2 recuperative Brayton cycle for hypersonic vehicles was proposed to meet the cooling requirements of each operating stage of a TBCC engine and to provide continuous power. Several optimization parameters able to balance the characteristics of the limited cold source, system weight, and power output of the system, such as the power-to-weight ratio and heat sink saving ratio, were proposed. With the help of optimization algorithms, the global performance curves and loads of each component were obtained during flights in the range of Mach 3.2~6. The recuperator heat duty and compressor inlet temperature were key design parameters that affected system performance. The compressor inlet temperature is known to alter the heat sink utilization by changing the pinch point location in the gas cooler. The recuperator heat duty impacted both the system weight and power generation. The dynamic performance of the system indicated that the minimum heat sink saving ratio was approximately 10% during the entire flight, implying that the volume of fuel carried by the hypersonic vehicle could be reduced to some extent, while sufficient electricity was generated. The proposed system is a novel solution for thermal protection of TBCC engines and aircraft power generation technology under limited cold-source conditions.
      原文链接:
    • NSTL
    • Elsevier

    Experimental study on the effect of rotation on melting performance of shell-and-tube latent heat thermal energy storage unit

    Chao YangZhang-Jing ZhengXiao CaiYang Xu...
    12页
    查看更多>>摘要：Rotation can effectively solve the problems of non-uniform melting and low melting rate in the shell-and-tube latent heat thermal energy storage unit (LHTESU). The current studies only focus on the numerical study of the rotating LHTESU and ignore the heat conduction of the outer shell. In this paper, a visual experimental investigation is conducted to intuitively compare the strengthening effect of different rotation modes (static, rotate, and flip) and further optimize the flipping time with limited additional energy consumption. Considering the conduct of the outer shell, the temperature distribution and phase interface position under different rotation conditions and different inlet temperatures are studied. The experimental results show that the flip can achieve a significant enhancement effect with negligible additional energy consumption. With the increase of the flipping time, the melting rate of LHTESU increases first and then decreases. The optimal melting performance is obtained when the dimensionless flipping time is 0.375. The total melting time is shortened by 35.42% and the thermal energy storage rate is increased by 54.50%, at the inlet temperature of 80℃. Moreover, the thermal performance of LHTESU can be further improved by adopting rotation strengthening measures. Compared with the best flipping condition, rotation can shorten the melting time by 19.35% and increase the thermal energy storage rate by 18.54%. Meanwhile, by increasing the inlet temperature from 80℃ to 90℃, the increase in thermal energy storage capacity and melting rate is about 5% and 50% respectively, and the reduction of melting time is about 65%. In addition, the phenomenon of re-solidification of liquid PCM and the conduct of the outer shell is experimentally observed for the first time.
      原文链接:
    • NSTL
    • Elsevier

    Numerical analysis of oxidation performance of basalt fiber bundle thermal flow-reversal reactor

    Rao KuangYanying LiuTingzhen AnYijun Shen...
    9页
    查看更多>>摘要：This paper uses Ansys Fluent software to conduct a two-dimensional numerical study on the oxidation performance of basalt fiber bundle thermal flow-reversal reactor (TFRR). The influence of inlet methane concentration, inlet flow rate and circulation period on the oxidation performance of TFRR is analyzed. The results show that the maximum temperature in the reactor increases significantly with the increase of inlet concentration and flow rate. At the same time, the lower limit of the concentration that can be handled by the reactor was studied, and it was found that the basalt fiber bundle TFRR can completely treat the gas with the concentration of 0.1%, under the operating parameters of t_c = 80 s, v_(in) = 0.65 m/s or t_c = 60 s, v_(in) = 1.0 m/s. In addition, the device was compared with the honeycomb ceramic TFRR in terms of economic efficiency. It was found that the clean development mechanism(CDM) emission reduction benefit of the former was 1.95 times than that of the latter, and the economic benefit of waste heat utilization was 2.5 times than that of the latter.
      原文链接:
    • NSTL
    • Elsevier

    Novel model predictive control by hypothetical stages to improve energy efficiency of industrial cooling tower

    Neha Kumari AgarwalPinakpani BiswasAnand Shirke
    14页
    查看更多>>摘要：Cooling towers are unit operations that are used in almost every industry to cool down process water either by natural draft or forced draft. The energy intensive components of cooling towers are draft fans and circulating pumps which in traditional practise run at full rated capacities throughout the year ignoring the underlying opportunities for energy savings. The efficiency of a cooling tower is a function of ambient air temperature, relative humidity and wet bulb temperature. This work brings out a novel model of cooling tower along with an energy harnessing control system based on prevailing climatic conditions thus improving the overall efficiency of the system. Based on analogy to a distillation column with hypothetical stages a model for cooling tower is developed. Then a model predictive control is designed to control the draft fan speed and pump flow rate of cooling tower based on climatic conditions. Both the model and control strategy was developed using Aspen Plus (V12.1), MATLAB (R2018b) and Simulink softwares and has been validated and trained based on plant operating data. The developed model was then tested at a pilot cooling tower facility of capacity 1 Ton of Refrigeration and was observed to attain approximately 30% reduction in energy consumption compared to the traditional operation.
      原文链接:
    • NSTL
    • Elsevier

    Novel principle for characterizing the material-level parameters of a thermoelectric generator module

    Hongrui RenChunping NiuZhenxuan FangYabo Zhao...
    9页
    查看更多>>摘要：Accurate characterization of all the three material-level parameters, i.e., thermal conductivity, Seebeck coefficient and electrical resistivity, is a premise for performance evaluation or degradation analysis of both the lab-made and commercial thermoelectric generator (TEG) modules. The recently reported quasi-steady-state (QSS) method can directly derive all the three temperature-dependent parameters through in situ TEG module characterization but shows a poor efficiency. This paper presents a modified QSS method based on stepped temperature rise for a high implementation efficiency. Both the optimal 'width' and 'height' of each step are elaborately specified. Its feasibility is then validated using a high-fidelity transient TEG model, which considers all the related effects and key irreversible factors. According to the simulations, the modified method has a 108 times higher efficiency than that of the original QSS method. Finally, the practicality of this modified method is explored by tests, which shows a consistent accuracy compared to the original method. Therefore, the modified QSS method is more practical, because it can greatly improve the efficiency on the premise of ensuring the accuracy with its similarity to the original QSS method. All the principle, method and conclusions can assist TEG performance estimation and guide the design of large-scale power systems.
      原文链接:
    • NSTL
    • Elsevier

    Heat-mass transfer coupling effects in water-ice phase transformation of water-bearing coal frozen with liquid nitrogen

    Min YanYiru FanMin YueJianing Wei...
    17页
    查看更多>>摘要：Liquid nitrogen (LN_2) fracturing, as a waterless and environmentally friendly fracturing technology, has a broad application prospect in coalbed methane (CBM) exploitation. Currently, there is a lack of sufficient understanding of the heat mass transfer mechanism of LN_2 fractured coal mass. In this paper, the heat-flow coupling problem of LN_2 frozen coal mass was systematically studied by means of numerical simulation. A fluid-solid coupled multiphase module was mathematically modeled on LN_2 flow, coupling between LN_2 and coal mass temperature, and the variation law of coal temperature and water-ice phase with time and geometric position during LN_2 flow was obtained under the coal seam freeze-thaw simulation analysis program by FORTRAN language. The results showed that the most obvious heat mass transfer occurred in the coal mass area close to the LN_2 inlet and the fluid-solid interface. Along the direction of coal burial depth, the changes of temperature and water-ice phase are broadly divided into rapid change zone, slow change zone and stable zone, and along the horizontal direction of LN_2 flow, the temperature and unfrozen water volume first peaked, then decreased and gradually stabilized, while the ice content was diametrically opposed, which indicating that the change of temperature and water-ice phase have significant anisotropic characteristics, and the hydrothermal coupling effect out to be one of the most important factors affecting the effect of LN_2 fracturing coal. The main findings of this study are the keys to the research of LN_2 fracturing physical mechanisms in CBM reservoirs.
      原文链接:
    • NSTL
    • Elsevier

    Heat transfer under high-power heat release: Not fully stable fluids as potential heat carriers

    Alexander IgolnikovSergey RutinPavel Skripov
    10页
    查看更多>>摘要：In this paper, we present new data on non-stationary heat transfer in sub- and supercritical liquids due to high-power heat release in a wire probe immersed in an investigated liquid. In the performed experiments, the characteristic heating time was from 5 to 180 ms, while the corresponding thickness of the heated layer was in the magnitude order of 10~1 μm. The impetus for the study came from the previous discovery of two unexpected effects. The first was a deterioration of heat transfer during the rapid transition of a compressed fluid to the supercritical region of temperatures along the isobar. The second was the distinctive character of the change in the heat flux density of a binary, partially miscible liquid when going deeper into the region of its unstable states. The study is aimed at clarifying the prospects of using supercritical fluids and mixtures with lower critical solution temperatures as potential heat carriers in processes where the possibility of powerful local heat release cannot be excluded.
      原文链接:
    • NSTL
    • Elsevier

    Investigation into the use of phase change materials in thermal management of a solar panel in the vicinity of tubes with slotted rectangular fins

    Jawed MustafaSaeed AlqaedMohsen Sharifpur
    27页
    查看更多>>摘要：In this paper, a thermal solar panel is simulated numerically. An enclosure of CaCl_2·6H_2O phase change material (PCM) is placed at the bottom of the panel in the presence of graphene nanoparticles. A tube is placed in the middle of the enclosure in which alumina-water nanofluid flows at the Reynolds numbers of 200 to 800. A number of fins are installed on the tube. The effect of using three different types of fins in a period of 0 to 5 h and Reynolds number on the panel temperature, PCM volume percentage, output nanofluid temperature, bottom panel thermal resistance, and panel temperature uniformity is examined. The finite element method is employed to solve governing equations. The results demonstrate that the best temperature uniformity on the solar panel occurs at Reynolds number of 800. The Reynolds number of 800 also has the lowest maximum temperature, average panel temperature, and thermal resistance. Using the Reynolds number of 800 instead of 200 reduces the PCM volume percentage from 93.14% to 23.40% and reduces the nanofluid output temperature by 4.3℃. Using fins case 3 creates the minimum temperature on the panel and minimum amount of thermal resistance. The fins case 3 and case 2 produce the minimum and maximum amounts of molten PCM.
      原文链接:
    • NSTL
    • Elsevier

    Energy, exergy, and entropy generation analyses of a water-based photovoltaic thermal system, equipped with clockwise counter-clockwise twisted tapes: An indoor experimental study

    Mohammad Reza KalatehAli KianifarMohammad Sardarabadi
    12页
    查看更多>>摘要：Nearly half of the insident solar radiation to the photovoltaic (PV) units will be converted to heat, which leads to a high operating temperature, cell structural damage, and the lifetime reduction. Therefore, an effective cooling method for these units is vital. The present work is the first experimental study on the influence of the twisted tapes (clockwise and counter-clockwise), which are inserted in riser tubes, on the performance of a photovoltaic thermal system from energy, exergy, and entropy generation viewpoints. In the indoor experiments, working fluid (pure water) with various flow rates ranged from 0.019 to 0.036 kg/s passed through the collector, where heat fluxes of 300, 500, 700, and 900 W/m~2 were applied on the surface of photovoltaic units. Thanks to utilizing twisted tape inserts with the flow rate of 0.019 kg/s, the average surface temperature decreased by 1.4, 1.2, 1.7, and 0.6℃, respectively, under heat fluxes of 900, 700, 500, and 300 W/m~2. In addition, the overall energy efficiency of the photovoltaic thermal system, using clockwise and counter-clockwise twisted tapes, increased by 7.37 and 68.97%, respectively, compared to that of the conventional photovoltaic thermal system and PV unit. From exergy viewpoint, the photovoltaic thermal system using twisted tapes experienced higher overall efficiency (14.86%) compared to that of the conventional photovoltaic thermal system (13.57%) and PV unit (11.57%). Furthermore, lower entropy generation belonged to the photovoltaic thermal system with twisted tape inserts.
      原文链接:
    • NSTL
    • Elsevier

    Thermal energy storage for increased waste heat recovery at a silicon production plant in Norway

    Daniel RohdeAnton BeckPaul WilpertSabrina Dusek...
    15页
    查看更多>>摘要：The production of silicon is an energy-intensive process, which requires high temperatures. Sudden release of high-temperature gas to the exhaust system is an inevitable part of silicon furnace operation and causes strong fluctuations in the waste heat recovery system. This makes waste heat recovery challenging and leads to frequent throttling of the produced steam reducing the efficiency of the system. To avoid this throttling and thus increase system efficiency, retrofitting a thermal energy storage to the existing waste heat recovery system is analyzed for a silicon production plant in Norway. A steam accumulator installed in parallel to existing bypasses, which does not interfere with the existing waste heat recovery system, is found to be ideally suited for the case. The analysis is carried out using real plant data, which is used to calibrate a dynamic simulation model modelled in the Modelica language. Design parameters of the steam accumulator are identified based on economic optimizations and their performance is verified with the dynamic simulation model. The simulation results shows that the simplifications in the economic optimizations are acceptable and that storage sizes of less than 10 m~3 can lead to annual profits of around 23 k{EUR}. Investment costs excluding transport and on-site installation are around 120 k{EUR}, yielding payback times from three to six years, depending on public funds. Including transport and on-site installation increases the payback times to about seven to ten years. The integration of a storage of this size was deemed realistic by the plant operators. The results will therefore be used for the creation of a business case with a more detailed cost analysis.
      原文链接:
    • NSTL
    • Elsevier