Investigation Of Thermal Performance Research Articles

Numerical investigation of thermal performance of single‐walled carbon nanotube nanofluid under turbulent flow conditions

In this paper, a numerical study is performed to investigate the effect of Reynolds number and nanoparticle concentration on the thermal performance of single‐walled carbon nanotubes (SWCNTs) nanofluids flowing through a straight pipe with constant heat flux in a turbulent flow regime. The governing equations (continuity, momentum, energy, rate of turbulent production, and rate of turbulent dissipation) are solved using a computational fluid dynamic approach (ie, finite volume method). In the sensitivity analysis, the Reynolds number is varied between (10 000‐200 000) and nanoparticle concentration between (0%‐0.25%). The simulation results show that convective heat transfer (average Nusselt number) increases by 7.48% while the pressure drop and pumping power increase by 119% and 199%, respectively. In addition, at low Reynolds number (104), increase in nanoparticle concentration (0%‐0.25%) decreases entropy production rate by 16.95%. However, at higher Reynolds number (2*105), the entropy production rate increases by 149.77%. Furthermore, other results such as entropy generation number, Bejan number, second thermodynamic law efficiency, and thermal performance factor, which combine the first and second law of thermodynamics, are presented as functions of Reynolds number and nanoparticle's concentration. The overall result shows that SWCNT nanofluid will only be beneficial at low Reynolds number of (10 000‐50 000).

Investigation of thermal performance of SAC variables using fuzzy logic based expert system

The thermal performance of a solar air collector (SAC) is investigated experimentally under the different climatic conditions of north eastern India using fuzzy logic based expert system (FLES). The FLES based on subtractive clustering (SC) with the fuzzy logic method where here, SC is used for extraction of optimal fuzzy IF-THEN rules while a fuzzy logic is used for modeling of SAC variables. This work considered four input variables [like mass flow rate (m), collector tilt angles (θ), solar radiation (Q), temperature (T)] and the four output variables [i.e. efficiency (η), exergetic efficiency (ηII), temperature rise (∆T), and pressure drop (∆P)]. First, 272 trials of experimentation on SAC are performed by varying m from 0.0078 to 0.0118 kg/s and θ from 30 to 60°, whereas the variation of metrological data is obtained in different working days. Then modeling and parametric analysis is carried out for SAC. Experimental results reveal that the value of η increases with the increase in m, Q, T and θ up to 45°. The higher value of m results in a higher value of ∆P and that reduces the value of ηII. Also, FLES model provides comparable and acceptable values for SAC. At last, validation of the FLES model is done via published data to confirm the results.

Numerical investigation of thermal and hydraulic performance in novel oblique geometry using nanofluid

To capitalize the advantage of oblique fin heat sink (OFHS) with Al2O3–water nanofluids of different volumetric concentration (1, 2, and 4%), a comprehensive computational analysis has been performed for OFHS with nanofluid through the single-phase modeling. The present investigation focuses on the full domain simulation because the conventional periodic computational model approach is unable to investigate the flow migration effect and predicts higher value of Nusselt number. Apart from the disruption of boundary layer, vortices are observed in the secondary oblique channel due to flow separation that promotes an additional heat transfer enhancement. Higher Severity of the flow migration and hence more non-uniformity of nanofluid flow rate through the primary and secondary channels was observed at higher Reynolds numbers. The increment observed in the average Nusselt number (Nuavg) at Re = 750 for OFHS is about 90% and 115% for water and 4% volumetric concentration of nanofluid respectively compared to conventional SCHS. Also, Al2O3–water nanofluid exhibits about 30% higher enhancement at 4% volumetric concentration at Re = 750 in the OFHS with compared to water. The increase in heat transfer exceeded the pressure drop penalty at all the Reynolds numbers.

Thermal performance investigation of a solar air heater having discrete V-shaped perforated baffles

In the present work, thermal performance of solar air heater (SAH) having discrete V-shaped perforated baffles as artificial roughness on absorber surface has been numerically investigated. The effect of relative blockage height (e/H) of proposed roughness on Nusselt number (Nu), friction factor (f) and thermo-hydraulic performance parameter (THPP) has been considered. Parametric investigation covers a range of roughness parameter viz. relative blockage height (e/H) from 0.3 to 0.6 and flow parameter, Reynolds number (Re) from 4000 to 18,000 at constant open area ratio of 23%, relative pitch ratio of 6 and angle of attack of 60○. Performance of SAH with proposed roughness has been compared with other roughness geometries investigated by other researchers. It is noticed that Nusselt number enhancement ratio (Nurat) and friction factor enhancement ratio (frat) are 4.24 and 14.73, respectively, and maximum values of THPP is found to be 2.24 at e/H = 0.4. Abbreviations: CFD: Computational fluid dynamics; LSCB: Least square cell based; RNG: Renormalisation group; SAH: Solar air heater; SIMPLE: Semi implicit method for pressure linked equation; THPP Thermo-hydraulic performance parameter

Numerical Investigation and Comparison of Thermal Performance of Ferrofluid in Different Closed Loop Configurations

This paper describes the free convection heat transfer capability of kerosene based ferrofluid flowing through a closed loop for assessing the thermal performance. Numerical investigations were performed using COMSOL Multi Physics 5.0 for comparing the heat transfer characteristics of ferrofluid flowing through three different closed loop geometrical configurations. The heat transfer performance of rectangular, oval and circular shape closed loop was evaluated under same input test conditions. Constant magnetic field was applied and time dependent numerical study was conducted for single-phase fluid flow. The fluid moves under the effect of Kelvin Body Force and maximum velocity of 5.68 mm/s has been found for oval shaped configuration. Temperature and velocity plots have been plotted for different lengths of time and results of investigation reveal that oval shaped configuration favors better output in terms of velocity generated and heat transfer.

Investigation of thermal and electrical performance in a salt gradient solar pond

The performance of a salt gradient solar pond (SGSP) invariably depends on the properties across its various zones. This paper presents an experimental study of salt diffusion, electrical and thermal performance of a trapezoidal-shaped SGSP. The variations of various parameters such as salt concentration, temperature gain, electrical conductivity (EC), thermal conductivity, density, specific heat and total dissolved solids (TDS) are studied across different zones of SGSP. This study reveals that for a given level of solar insolation, the rate of temperature gain within the lower convective heat zone (LCHZ) is high during the initial stages of operation where the salt diffusion rate is slow. Temperature gain of 16.06° is observed during a month comprising both rainy and sunny days. Within LCHZ, it is found that thermal conductivity, density and specific heat depend strongly on the salinity and their dependence on the temperature is relatively weaker. However, the effect of temperature on these three parameters is observed in the upper convective cold zone (UCCZ). Additionally, in UCCZ and LCHZ, TDS and EC depend on both salinity and temperature. The present observations are proposed to be useful in applications related to solar pond based desalination and energy generation.

Experimental and numerical investigations of a single and double pass porous serpentine wavy wiremesh packed bed solar air heater

This research work presents the thermal performance investigation of a porous serpentine wavy wiremesh packed bed solar air heater, experimentally and numerically. Experimental results revealed the best thermal and thermohydraulic efficiencies for 93% porous double pass serpentine packed bed solar air heater and found to be about 80% and 74%, respectively, which is about 18% and 17% high compared to single pass, respectively. Whereas, numerical investigation is carried out on a CFD tool and the results are validated with experimental data. The range of porosity from 85% to 95%, wavelength from 0.05 m to 0.075 m, amplitude from 0.012 m to 0.016 m, hydraulic diameter from 0.025 m to 0.046 m and mass flow rate from 0.01 to 0.05 kg/s is considered to obtain optimum values for geometrical and flow parameters on the basis of THPP and exergy efficiency. The numerical results present the maximum 24.33% better thermohydraulic performance for serpentine packed bed solar air heater when compared to flat packed bed solar air heater. The wavelength of 0.075 m, amplitude of 0.012 m, hydraulic diameter of 0.0835 m, porosity of 90%, and mass flow rate of 0.03 kg/s is obtained as the optimum configuration.

A novel shell-and-tube thermal energy storage tank: Modeling and investigations of thermal performance

Utilizing the solar energy by thermal energy storage (TES) system is an important way to solve energy shortage and environmental pollution. In this paper, the air and nitrate salt have been selected as the heat transfer fluid (HTF) and phase change material (PCM), respectively, and the aim is to investigate the heat transfer performance of the storage tank. According to analyze the disadvantages of traditional cylindrical shell-and-tube TES tank, a novel truncated cone shell-and-tube TES tank has been established, and a new parameter namely Taper has been proposed. Meanwhile, the melting process of the TES tanks have been investigated by FLUENT software, and then the optimal TES tank with a Taper of 0.2072 has been obtained by comparing with the melting process of the four kinds of the truncated cone model. This research will provide theoretical guidance for future designing optimization of TES system for concentrated solar power (CSP) pant.

Thermal performance investigation of three sides concave dimple roughened solar air heaters

A novel work conducted upon three sides concave dimple roughened SAHs is presented here. Exhaustive experimental investigations were carried out in Feb-May 2017 upon one and three sides roughened solar air heaters on test setup installed at terrace of Mechanical Engineering Dept., NIT Jamshedpur and results are presented as rise in heat transfer and thermal performance of three sides over one side roughened duct against corresponding frictional losses. The experimental setup was validated using Nusselt number and friction factor correlation derived by Saini and Verma (2008) using one side roughened similar duct model. The geometrical parameters were used as dimensionless ratio as relative dimple pitch (p/e), relative dimple height (e/Dh) and relative dimple depth (e/d) in the range of 8–15, 0.018–0.045 and 1–2 respectively. The range of Reynolds number covered during experimentation was 2000–13500. Heat transfer augmentation for three sides over one side roughened ducts was appreciable considering rise in frictional losses. The thermal efficiency was measured in terms of collector heat removal factor (FR) and collector efficiency factor (F') and the collector’s performance parameters were given as FRτα and (FRUL). The optimum roughness parameter was found to be p/e = 12, ‘e/Dh’ = 0.036 and ‘e/d’ = 1.5. For ṁ = 0.0293 kg/s and Cp = 1.005 kJ/kg K, FRτα and FRUL comes out equal to 0.7346 and 8.85 W/m2 K, respectively. Three sides roughened SAHs have high thermal efficiency of the order of 44–67% more than that of one side roughened SAH for the range of flow and roughness parameters investigated.

An Experimental Investigation of Electrical and Thermal Performance of Battery Pack for Zero Emission Vehicle

A motor transport is a leading cause of the negative ecological situation and the excessive use of non-renewable resources. Increasing the volume of emissions from the operation of internal combustion engines and increasing consumption of hydrocarbon fuel are factors that stimulate the development of electric vehicles which are environmentally friendly and energy efficient. However, today electric vehicles are difficult to counter conventional cars in terms of cost and performance, determined mainly by characteristics and operating modes of traction battery packs. This article considers some topical issues related to the practical implementation of traction battery packs based on lithium-ion cells. The electric and thermal characteristics of the battery pack are considered by the authors in conditions of a discharge mode simulation. This is believed to be a the technical solution for the implementation of a modular battery pack, The present experimental investigations give qualitative and quantitative evaluation of the heat release of lithium nickel manganese cobalt oxide (NMC) cells and demonstrate the efficiency of the realized passive air cooling. This article partly fills the gap existing with regard to real (experimental) data on temperature conditions and heat release of NMC-cells in battery packs of electric vehicles.

Thermal performance investigation of an integrated collector–storage solar air heater on the basis of lap joint-type flat micro-heat pipe arrays: Simultaneous charging and discharging mode

In this part of the investigation, the thermal performance of an integrated collector–storage solar air heater (ICSSAH) on the basis of a lap joint-type flat micro-heat pipe array during simultaneous charging and discharging mode is experimentally studied. Paraffin is used as a phase change material, and air acts as a heat transfer fluid in a built-out structure of ICSSAH. The thermal performance of ICSSAH is assessed under an outdoor experiment to explore the effect of seasonality, volume flow rate, and daily accumulative solar radiation. Thermal energy analysis is described and calculated in detail according to the experimental measurements. Results showed that the daily mean thermal efficiency in summer is significantly higher than the transition season. The smaller the volume flow rate is, the lower the thermal efficiency will be. However, the effect of solar radiation on thermal efficiency is small during the test conditions. The highest daily thermal efficiency at the volume flow rate of 141 m3/h is approximately 78.1% in the present study when the solar irradiance ranges from 0 W/m2 to 874 W/m2 and the ambient temperature varies from 27.8 °C to 35.4 °C.

Drywall Waste Blocks: A Novel Masonry Material Utilizing Recycled Construction & Demolition Waste

This paper describes patent-pending mixtures and methods for producing masonry blocks using gypsum drywall waste and preliminary investigation of Drywall Waste Block (DWB) engineering properties. Recycling waste from building construction and demolition (C&D) provides many environmental and economic benefits. However, challenges remain for recycling certain low-value C&D materials, such as gypsum drywall waste, and there are few uses for drywall waste from demolition, which constitutes the majority of the drywall waste stream. Recycling drywall waste is desirable as this waste produces noxious hydrogen sulphide gas in landfill conditions, resulting in bans on landfilled drywall waste in some localities. Investigation of compressive strength, water absorption, and thermal performance of DWB specimens is described, and results are compared to specifications for concrete masonry units (CMU), and other comparable masonry blocks. Technical gaps for DWB to be recognized as a CMU alternative are also discussed.

Numerical investigation of thermal performance of geometrically modified spherical ice capsules during the discharging period

Ice thermal energy storage (ITES) is a significant option for shifting cooling load from peak hours to off-peak hours in order to reduce the cooling cost and equipment capacity. Encapsulated ITES system is one of the most preferred types of ITES systems, because it is easier to apply and has lower initial cost than other types of ITES systems. Capsule geometries have great impact on the thermal performance of the encapsulated ITES system. Spherical capsules are widely used in the application because they provide better thermal performance due to the ratio of its volume to its surface area. Also, modified capsule geometries are used for increasing the thermal performance of the ITES system. This paper focuses on a numerical study in order to determine the effect of the geometrically modified spherical capsule on the thermal performance during the discharging period. Seven geometrically modified spherical capsules were investigated and compared with the ordinary spherical capsule. The FLUENT 17.1 code was used for numerical analyses. At the end of the study, it was found that geometrically modified capsules provided higher thermal performance than an ordinary spherical capsule in the equal capsule volume. Capsule D provided the longest discharging period of 2118 seconds, when VHTF, in = 0.001 m/s and THTF,in = 275.5 K. The lowest discharging time of 464 seconds was obtained with Capsule A, when VHTF, in = 0.01 m/s and THTF, in = 283 K. Among the studied modified capsules, Capsule F performed the worst thermal performance. Energy efficiency values were high, and they did not give comparable difference between the capsule models and working conditions. While all exergy values were 98.50% and higher, exergy efficiency values changed between 85.12% and 51.91%. Exergetically, Capsule D provided the best thermal performance during the discharging period.

Thermal and energy performance investigation of a smart double skin facade integrating vanadium dioxide through CFD simulations

Double skin facades (DSFs) are known by their capacity to generate a natural heating energy during winter by increasing the greenhouse effect in the air cavity between the inner and the outer facade. However, this effect provides an undesirable overheating during summer. In this study, a smart DSF configuration able to control the greenhouse effect generation was numerically simulated using a two dimensional Computational Fluid Dynamic (CFD) method. The aim of these simulations is to investigate the thermal and the energetic behavior of a DSF integrating Tungsten (W) doped Vanadium dioxide (VO2) as an optically smart thin material and a high absorbing aluminum nitride (AlN) coating. A parametric study was carried out in order to analyze the impact of the air cavity thickness on the smart DSF behavior. Four thicknesses (10, 25, 50 and 75 mm) were inspected and compared with an uninsulated massive wall configuration. Results have shown that the smart configuration reduces significantly both heating and cooling loads. Indoor surface temperature has been decreased by around 2 °C during summer and increased by around 3 °C during a sunny winter day. The air velocity results have shown that the natural convection-radiation interaction during winter is higher than during summer. Thus, the new smart DSF configuration presented in this paper can effectively control the greenhouse effect depending on external climatic conditions.

Experimental Investigation of Thermal and Hydraulic Performance of a Plate Heat Exchanger Using Nanofluids

Gasketed plate heat exchangers (PHEs) occupy a crucial position in the energy sector due to their efficient and compact design. A number of studies have focused on making the plate heat exchangers more efficient and compact, since energy usage increases day by day. Therefore, the idea of utilizing nanofluids, whose thermophysical properties are better than those of industrial fluids, have drawn the attention of researchers. An experimental setup was designed and constructed at the TOBB ETU Heat Exchangers Laboratory to investigate the effect of utilizing nanofluids in a plate heat exchanger. The experiments were performed with three different working fluids, namely, tap water and 1 and 0.5 wt.% Al2O3/water nanofluids in a hot cycle. For all cases, the flow rates were 100–450 L/h, and the experiments were repeated three times for accuracy. As a result of this study, new correlations for the Nusselt number and heat transfer enhancement rates were obtained. Moreover, the friction factor correlations were found for all cases, and the effect of nanofluids on the pressure drop has been revealed.

Experimental investigation of thermal performance of the oscillating heat pipe for the grinding wheel

A massive amount of heat is generated during the high-efficiency grinding process, which leads to a serious burnout problem that limits the increase of the material removal rate. The oscillating heat pipe (OHP) can augment the heat transfer in the grinding zone to avoid the burnout. An oscillating heat pipe grinding wheel that is a combination of a grinding wheel and OHPs was proposed in this paper. Aimed to determine geometric dimensions and operating parameters of the OHP, experimental investigations were carried out to study effects of working fluid, inner diameter, and heat flux on the heat transport capability of OHPs. The dynamics of flow change and coupled effects of geometric dimensions and thermophysical properties of working fluids were further analyzed by visualization. The OHP filled with acetone shows an advantage in heat transfer. Within the critical diameter range, a large inner diameter is better for the thermal performance. As heat flux increases, changes of flow pattern and motion modes from bubbly flow to annular flow and from oscillation to circulation enhance the thermal performance. The inner diameter of 3 mm and acetone as the working fluid are preferred for better cooling effects.

Thermal performance investigation of an air-cooled lithium-ion battery pack considering the inconsistency of battery cells

A lithium-ion battery pack is the power source of an electric vehicle, and its temperature rise is one of the main concerns. Existing research mainly focused on the design of cooling systems, and always used computational fluid dynamics to analyze the thermal behavior of batteries, regardless of the individual differences of batteries. In this paper, the heat dissipation performance of air-cooled battery packs considering the different thermal performance of different batteries was studied. A more realistic thermal model of the battery pack at 1C discharge rate was obtained through equivalent calculation and experimental verification. The results showed that the temperature of batteries with different thermal performance rose faster and the temperature difference was larger. At the same time, the thermal performance of the battery can be improved by placing the outlet and inlet on the same side. The thermal performance was more sensitive to the inlet exhaust height than to the outlet exhaust height. The research results can provide a basis for exploring the design method of battery packs with better heat dissipation performance, lower energy consumption, and a smaller volume.

Investigation of Thermal Performance of Cylindrical Heat Pipe Using Silver Nanofluid. Part I: Experimental Evaluation

Cylindrical heat pipes are widely used in various applications to transfer the heat effectively and efficiently. Besides parameters of heat pipe, its thermal performance mainly depends on the characteristics of working fluid also. Recently, various nanofluids have been considered as the most promising working fluid in different heat transfer applications. In the present paper thermal performance of cylindrical heat pipe using silver nanofluid as working fluid has been experimentally evaluated. Extensive experiments have been performed on cylindrical copper heat pipe having two-layer screen mesh filled with silver nanofluid in filling ratio of 40% with a vacuum of 10−3 torr. The thermal performance of heat pipe has been evaluated in terms of thermal resistance, thermal conductivity and overall heat transfer coefficient by varying parameters such as size of nanoparticle, concentration of nanoparticle, angle of inclination of heat pipe, heat load on heat pipe, average evaporator temperature and average condenser temperature to propose the best combination of parameters. The results indicate that the cylindrical heat pipe kept at 45° inclination angle and filled with silver nanofluid of 35 nm size of silver nanoparticle in 0.3% volume concentration yields higher thermal performance when it is operated at 120–140 W heat input. Thus, the cylindrical heat pipe under study is suitable for applications which require operation of heat pipe at some angles, such as cooling of high-wattage LED street lights.

Investigation of Thermal Performance of Cylindrical Heat Pipe Using Silver Nanofluid: Part-II: Prediction Using Artificial Neural Network

Heat pipes are one of the heat transfer devices adopted in various applications due to its high heat transfer capability. Recently, heat pipes are charged with different nanofluids to increases its performance. Thermal performance of heat pipe charged with nanofluids depends of various factors related to operating conditions, working fluids, heat pipe, etc. Thus, extensive experimentation work is required to recommend appropriate parameters for different industrial applications. In such cases, in order to reduce experiments and to propose the appropriate combination of parameters, experimentation results need to be modeled using fundamentals of simulation. In the Part I of the paper, extensive experiments have been carried out on cylindrical heat pipe with silver nanofluid as working medium. In the present paper, total of 96 artificial neural network models have been created and trained on the basis of the total 700 data sets presented in Part I of the paper. Out of 700 data sets, eight data sets have been randomly separated for post-training simulation of the model, while 692 data sets have been employed for formulating the ANN model using the ANN tool of MATLAB student version available at the college. The models have been prepared to predict the thermal performance of cylindrical heat pipe under study when one, two and three parameters have been considered as output neurons one by one and six parameters as input neurons. Out of six input parameters, heat load, average evaporator and average condenser temperature are related to operating condition, size and concentration of silver nanoparticles are related to working fluid, and inclination angle is related to position of heat pipe. Trained 96 ANN models have been simulated using eight data sets, and the best ANN model has been proposed on the basis of minimum value of error in prediction in terms of MSE, NMSE, MAE, MARD and MRE. The best ANN model identified for one, two and three output neurons is single-layer feed-forward backpropagation network with six neurons of hidden layer, cascade feed-forward backpropagation network having three neurons at hidden layer and single-layer feed-forward backpropagation network with 12 neurons of hidden layer, respectively. It is also concluded that for single output neuron, any one type of error in prediction can be considered to select the best ANN model. But for more number of output neurons, comparison of various types of error in prediction is essential to judge the best ANN model.

Potential of adaptive neuro-fuzzy methodology for investigation of heat transfer enhancement of a minichannel heat sink

In this paper, the potential of adaptive neuro fuzzy inference system (ANFIS) was appraised for investigation of thermal performances of a minichannel heat sink for cooling of electronics using nanofluid coolant instead of pure water. The process, which simulates the thermal performances with ANFIS network, was constructed. The developed ANFIS network was with three neurons in the input layer, and one neuron (thermal performances) in the output layer. Since there are three thermal performances investigated, three ANFIS networks are created. The inputs were flow rate, as well as the Reynolds number. The third input represents the nanofluid concentration. The Al2O3–H2O nanofluid including the volume fraction was used as a coolant. Obtained experimental results showed the higher improvement of the thermal performances using nanofluid instead of pure distilled water. ANFIS results show that an improvement in predictive accuracy and capability of generalization can be achieved by the ANFIS approach for heat sink base temperature prediction.