Volume 8B: Heat Transfer and Thermal Engineering最新文献

{"title":"Experimental Investigation on Flow Field in a Rotating Channel With a New TR-PIV System","authors":"Shengjun Zhou, Haiwang Li, Z. Tao, Ruquan You, Haoyu Duan","doi":"10.1115/IMECE2018-86976","DOIUrl":"https://doi.org/10.1115/IMECE2018-86976","url":null,"abstract":"In the current study, the influence of different rotation conditions on the flow behavior is experimentally investigated by a new system which is designed for time-resolved PIV measurements of the smooth channels at rotation conditions. The Reynolds number equals 15000 and the rotation number ranges from 0 to 0.392 with an interval of 0.098.\u0000 This new time-resolved Particle Image Velocimetry system consists of a 10 Watts continuous laser diode and a high-speed camera. The laser diode can provide a less than 1mm thickness sheet light. 6400 frames can be captured in one second by the high-speed camera. These two parts of the system are fixed on a rotating disk. In this case, the relative velocity of flows in the rotating smooth square channel can be measured directly to reduce the measurement error. This system makes high-speed camera close to the rotating channel, which allows a high resolution for the measurements of main stream. In addition, high accuracy and temporal resolution realize a detailed analysis of boundary layer characteristics in rotation conditions. Based on this system, experimental investigation has been undertaken. Results are presented of the evolution of velocity and boundary layer thickness at various rotation numbers and different circumferential positions.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"265 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114648282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-Scale Modeling of Power Plant Performance Enhancement Using Asynchronous Thermal Storage and Heat Rejection","authors":"Lauren Gagnon, Dre Helmns, V. Carey","doi":"10.1115/IMECE2018-88107","DOIUrl":"https://doi.org/10.1115/IMECE2018-88107","url":null,"abstract":"The study summarized in this paper links a model of thermal energy storage (TES) unit performance to a subsystem model including heat exchangers that cool down the storage at night when air temperatures are low; this cool storage is subsequently used to precool the air flow for a power plant air-cooled condenser during peak daytime air temperatures. The subsystem model is also computationally linked to a model of Rankine cycle power plant performance to predict how much additional power the plant could generate as a result of the asynchronous cooling augmentation provided by this subsystem. The goal of this study is to use this model to explore the parametric effects of changing phase change material (PCM), melt temperature, and the energy input and rejection control settings for the system. With this multi-scale modeling, the performance of the TES unit was examined within the context of a larger subsystem to illustrate how a high efficiency, optimized design target can be established for specified operating conditions that correspond to a variety of applications. Operating conditions of interest are the mass flow rate of fluid through the flow passages within the TES, the volume of the TES, and the amount of time the system remains in the extraction process in which thermal energy is inputted to the device by melting PCM, and the PCM melt temperature. These conditions were varied to find combinations that maximized efficiency for a 50 MW power plant operating in the desert regions of Nevada during an average summer day. By adjusting the flow rate within the fluid flow passages and the volume of the TES to achieve complete melting of the PCM during a set extraction time, indications of the parametric effects of system flow, melt temperature, and control parameters were obtained. The results suggest that for a full-sized power plant with a nominal capacity of 50 MW, the kWh output of the plant can be increased by up to 3.25% during the heat input/cold extraction period, depending on parameter choices. Peak power output enhancements were observed to occur when the system operated in the extraction phase during limited hours near the peak temperatures experienced throughout a day, while total kWh enhancement was shown to increase as the extraction period increased. For the most optimized conditions, cost analyses were performed, and it was estimated that the TES system has the potential to provide additional revenue of up to $1,366 per day, depending on parameter choices as well as the local cost of electricity. Results obtained to date are not fully optimized, and the results suggest that with further adjustments in system parameters, weather data input, and control strategies, the predicted enhancement of the power output can be increased above the results in the initial performance predictions reported here.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129542220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Cooling Process of Agricultural Products After Boxing and Palletizing","authors":"A. Giorges, J. Pierson","doi":"10.1115/IMECE2018-87788","DOIUrl":"https://doi.org/10.1115/IMECE2018-87788","url":null,"abstract":"Assuring that food products have acceptable quality and are safe to consume requires maintaining adequate nutrition levels and fulfilling consumer expectations. Quality losses can lead to food waste, resulting in increased economic costs and low consumer confidence. Therefore, quality expectations should be maintained at an acceptable level for consumer purchase and consumption. It is well known that a cold environment reduces the respiratory activities and kinematics of nutritional degradation. The cooling temperature is critical since lower than recommended cold temperatures may cause chill damage. Therefore, the food industry intensively employs cold storage methods to slow respiration rates, inhibit harmful bacterial growth, reduce water loss, and prolong shelf life in order to maintain product nutritional value and quality. Improving product cooling efficiency will reduce energy costs that are a significant expense for fruit and vegetable processors. Understanding the cooling process is key to the development of new technology and processes. However, most natural food products are not conformed to simple geometric shapes or uniform properties and distributions. Thus, the cooling process of an agricultural product (cucumbers) was investigated in this study. The study was conducted in a packing house, where the cooling temperature of the cucumbers was recorded by placing multiple thermocouples in the produce after boxing and palletizing as well as cold storage. The test results showed that individual produce cooling was relatively easy to predict. However, boxed and palletized cucumber cooling showed significant variations. For example, the temperature of the cucumbers changed depending on their location in the box in addition to the box location on the stack. In the case of boxed produce cooled by natural convection cooling, the temperature changed from 25 to 18 °C after three hours. However, in the case of palletized tunnel cooled, the temperature change ranged from 25 to 11 °C and 25 to 18 °C after nearly three hours of cooling. Indeed, the temperature differences indicated that the cooling rate has significant variations depending on the location of the produce. Some parts of the pallet received more direct contact with the forced cold air than other parts. Thus, it is very important for produce processors to understand cooling system performance. The study emphasized that efficient use of energy is one of the areas that can have not only significant cost savings but can also improve produce shelf life, reduce food waste, and maintain consumer confidence.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126348978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Comprehensive Parametric Study of Minichannel Based Liquid Cooling of Li-Ion Battery Pack","authors":"Z. An, K. Shah, Yanbao Ma, Jia Li","doi":"10.1115/IMECE2018-87923","DOIUrl":"https://doi.org/10.1115/IMECE2018-87923","url":null,"abstract":"Li-ion based energy storage devices have highly temperature dependent characteristics such as performance, life-cycle, efficiency and safety. Large temperature gradient within a cell results in thermal stresses and nonuniform current density leading to accelerated degradation. This adversely affects the life cycle of the cell due to capacity and power fade. There are similar issues due to large temperature variation within a battery pack. Operation of Li-ion cell outside the desirable temperature range also leads to lower efficiency, degradation and safety related issues. Different thermal management approaches have been proposed and demonstrated in past. The present work focuses specifically on minichannel based liquid cooling for conducting a parametric study. Minichannels have been found effective in various thermal management applications due to their simple construction and high convective heat transfer. In past, minichannels have been proposed and used in battery thermal management. However, designing of such systems has been somewhat arbitrary without considering various factors and trade-offs involved. There is a lack of rigorous studies for determining various parameters related to thermal management system that would result in adequate thermal management in a cost-effective manner. In the present work, a comprehensive parametric study has been carried out on the minichannel based liquid cooling for thermal management of Li-ion battery pack. A simplified computationally efficient numerical simulation-based approach has been used to conduct parametric study for optimizing the design and operating parameters of the thermal management system.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127646353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat Transfer by a Rotating Liquid Jet Impingement Cooling System","authors":"Qi Lu, S. Parameswaran, B. Ren","doi":"10.1115/IMECE2018-88377","DOIUrl":"https://doi.org/10.1115/IMECE2018-88377","url":null,"abstract":"The circular, liquid jet impingement provides a convenient way of cooling surfaces. To effectively cool the devices inside the electric vehicle, a rotating jet impingement cooling system is designed to evaluate the potential of the jet impingement for high heat flux removal. The liquid used for jet impingement is automatic transmission fluid. The jet impingement system consists of a rotating pipe with two nozzles and a cylindrical ring which is attached to the heat source. To reduce the computational loads, first, the CFD simulation for a laminar flow inside the pipe is carried out to estimate the flow velocities at the nozzle exits. Then, the rotating jet impingement cooling of a cylinder with a uniform surface temperature is investigated numerically for stable, unsubmerged, uniform velocity, single phase laminar jets. The numerical simulation using the commercial code is performed to determine the heat flux removal performance over the cylindrical surface. The numerical results are compared with the empirical formula and experimental measurements from the literature. Furthermore, the effects of the Reynolds number and pipe rotation on the jet impingement cooling performance are also investigated.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"369 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124628677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility Study of Effective Cooling Through Microchannel Heat Sink (MCHS) and Nanofluid Applications","authors":"D. Jennings, Sonya T. Smith","doi":"10.1115/IMECE2018-88690","DOIUrl":"https://doi.org/10.1115/IMECE2018-88690","url":null,"abstract":"The goal of this research is to present an analytical model of nanostructures and study the effects of their geometry on the performance of micro channels. The pressure drop experienced by micro channels is of interest as it presents a limit on forced convection heat transfer. This work will demonstrate how the presence of nanostructures alleviates pressure drop and results in enhanced cooling capabilities. Multiple transient analyses were performed in ANSYS FLUENT to ascertain performance characteristics of microchannels without the presence of hydrophobic nanostructures. The results were compared to the analytical model developed in this study.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124786795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Investigation on Boundary Layer Flow Under the Effect of Temperature Gradient in a Smooth Rotating Channel Using Hot-Wire","authors":"Gangfu Li, Z. Tao, Huijie Wu, Ruquan You, Haiwang Li","doi":"10.1115/IMECE2018-87183","DOIUrl":"https://doi.org/10.1115/IMECE2018-87183","url":null,"abstract":"This experiment measures the temperature and the velocity field synchronously in the boundary layer in a rotating smooth, wall-heated channel using hot-wire. The Reynolds number based on the bulk mean velocity and hydraulic diameter is 19000 and the rotation numbers are 0, 0.07, 0.14, 0.21, 0.28 and 0.35. Four streamwise stations (X/D = 4.06, 5.31, 6.56, 7.81) were investigated. To calibrate the parallel-array hot-wire probe, a heating section is added to the original wind tunnel that could only calibrate the hot-wire at room temperature. Different gas temperatures at the outlet could be obtained by changing the heating power of the heating section. The velocity profiles and the temperature profiles are obtained. It can be seen that the viscous sublayer also exists when the wall is heated, thus the viscous sublayer profile method is also valid when the wall is heated. It is found that the velocity profile near the leading side is more sensitive to the change of rotation number and X/D than the velocity profile near the trailing edge. The critical rotation number phenomenon of velocity profile has also been found in present work. By comparing with the previous work without the wall heated, the influence of both kinds of buoyancy under this condition is discussed. Some explanations are given for the experimental results.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116728990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermohydraulic Effect of Aspect Ratio on Combination Angled Dimpled in a Rectangular Channel","authors":"S. A. Aasa, T. Jen","doi":"10.1115/IMECE2018-86558","DOIUrl":"https://doi.org/10.1115/IMECE2018-86558","url":null,"abstract":"Solar thermal panels’ heat enhancement through cooling techniques is important for the effective use of the panels. This study is performed on a simulated internal cooling channel of a solar thermal cell with an artificial technique using angled dimpled rough end-wall and exploring the combination of the different geometrical surface to enhance the heat transfer from the wall. Circular and oval shape dimples combination arranged in staggered form are tested. However, the oval geometrics are varied typical to flow direction. The following combinations of circular and oval dimpled are therefore examined (1) 90° circular by 90° oval dimples to the mainstream (2) 90° circular by 60° oval dimples to the mainstream (3), 90° oval by 90° circular dimples to the mainstream and (4) 60° oval by 90° circular to the mainstream. All of which are having pitch/depth ratio, P/δ of 6, dimple centre to centre, P, of 30 mm, and print diameter, D, of 20 mm (for both circular and oval shape), oval small diameter of 10 mm. These combinations are tested for three aspect ratios of 0.049, 0.035 and 0.0249. This study is conducted for a Reynolds number range of 1,000–11,000, and local and averaged heat transfer coefficient values are presented for all the geometries. Pressure drops are measured along the mainstream of the smooth and dimpled channel end-wall and friction factors are calculated. The combination of the 60° oval and 90° circular dimple surface exhibits the best performance of all the cases considered, a moderate pressure drop was also observed compared with others like a combination of pin fins, ribs-protrusions, grooves etc. These values were higher or comparable to the best-performing dimple geometries commonly used for the internal cooling process.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"142 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129330202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Natural Convection in a Square Cavity Utilizing Different Nanofluids in Presence of Constant Magnetic Field With Brownian Motion Effect","authors":"M. Abdelaziz, W. El-Maghlany, A. S. Ismail","doi":"10.1115/IMECE2018-87123","DOIUrl":"https://doi.org/10.1115/IMECE2018-87123","url":null,"abstract":"Natural convection in a square cavity filled with water-Al2 O3 nanofluid is studied numerically. Upper, lower, and left surfaces are insulated. Right wall is at low temperature, while two heat sources are kept at high temperature. The sources are vertically attached to the horizontal walls of a cavity . A uniform magnetic field is applied in a horizontal direction. Effective thermal conductivity and viscosity of nanofluids are obtained using Koo-Kleinstreuer model which implements the Brownian motion of nanoparticles effect. Steady state laminar regime is assumed. The conservation of mass, momentum, and energy equations are solved using finite volume method. The numerical results are reported for the effect of Rayleigh number, solid volume fraction, and Hartmann number on the streamlines as well as the isotherms. In addition, the results for average Nusselt number are presented for various parametric conditions. This study is presented in the following ranges, Rayleigh number from 103 to 105, Hartmann number from 0 to 60, and solid volume fraction from 0 to 0.06, while the Prandtl number which represents water is kept constant at 6.2. The results showed that heat transfer rate decreases with the rise of Hartmann number and increases with the rise of Rayleigh number, and volume fraction. Moreover, results showed that heat sources positions, lengths and intensities have crucial effect on heat transfer rate. Additionally, the effect of nanofluids type was studied, it was found that water-Cu nanofluid enhances the heat transfer better than water-Al2O3, water-CuO and water-TiO2 nanofluids.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131026210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Pattern Geometry of Hybrid Surfaces on Dropwise Condensation Heat Transfer and Droplet Dynamics","authors":"Karim Egab, Saad K. Oudah, Mohammad Alwazzan, J. Khan, Chen Li","doi":"10.1115/IMECE2018-88571","DOIUrl":"https://doi.org/10.1115/IMECE2018-88571","url":null,"abstract":"The scope of combining two wettability regions is to impact the droplet dynamic behaviors, manipulate the droplets’ mobility and enhance condensation heat transfer. Hydrophobic-hydrophilic hybrid patterns can promote the heat transfer, droplet-renewal frequency and enhance the droplets’ removal during condensation. With regard of condensation on hybrid surfaces, the geometry of the patterns has a significant influence on droplets departure frequency and heat transfer performance. Therefore, different patterns geometries (circle, ellipse, and diamond) have been developed on horizontal copper tubes at atmospheric pressure. All the patterns have the same size, and the same identical gap as well between the adjacent patterns. Results show that the diamond hybrid surface has the best performance compared with ellipse, circles hybrid surfaces at the same pattern area with same neighbor gap between two patterns and complete dropwise However, the circle and ellipse hybrid surfaces outperform lower performance compared to complete dropwise surface. The heat transfer rate for the diamond hybrid surface is 15% higher than complete dropwise surface when the gap is 0.5mm. This study clearly demonstrated the effect of pattern’s geometry regarding maximum condensation heat transfer rate and droplet departure frequency.","PeriodicalId":307820,"journal":{"name":"Volume 8B: Heat Transfer and Thermal Engineering","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133456487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}