Energy Efficient Hybrid Nanofluids for Tubular Cooling Applications

2014 ◽  
Vol 592-594 ◽  
pp. 922-926 ◽  
Author(s):  
Devasenan Madhesh ◽  
S. Kalaiselvam
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Volume Concentration ◽  
Thermal Characteristics ◽  
Hybrid Nanofluid ◽  
Tubular Heat Exchanger ◽  
Overall Heat Transfer Coefficient ◽  
Flow Through ◽  
Hybrid Nanofluids

Analysis of heat transfer behaviour of hybrid nanofluid (HyNF) flow through the tubular heat exchanger was experimentally investigated. In this analysis the effects of thermal characteristics of forced convection, Nusselt number, Peclet number, and overall heat transfer coefficient were investigated.The nanofluid was prepared by dispersing the copper-titania hybrid nanocomposite (HyNC) in the water. The experiments were performed for various nanoparticle volume concentrations addition in the base fluid from the range of 0.1% to 1.0%. The experimental results show that the overall heat transfer coefficient was found to increases maximum by 30.4%, up to 0.7% volume concentration of HyNC.

scholarly journals Design of Flue Gas-Air Heat Exchanger for Regeneration of Desiccant System

2018 ◽  
Vol 225 ◽  
pp. 05006 ◽  
Author(s):  
Shaymaa H. Abdulmalek ◽  
Hussain H. Al-Kayiem ◽  
Aklilu T. Baheta ◽  
Ali A. Gitan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Waste Heat ◽  
Thermal Characteristics ◽  
Tube Diameter ◽  
Fuel Gas ◽  
Overall Heat Transfer Coefficient ◽  
Heat Exchanger Design

Heat recovering from biogas waste energy requires robust heat exchanger design. This paper presents the design of fuel gas-air heat exchanger (FGAHE) for recovering waste heat from biogas burning to regenerate desiccant material. Mathematical model was built to design the FGAHE based on logarithmic mean temperature difference (LMTD) and staggered tube bank heat transfer correlations. MATLAB code was developed to solve the algorithm based on overall heat transfer coefficient iteration technique. The effect on tube diameter on design and thermal characteristics of FGAHE is investigated. The results revealed that the smaller tube diameter leads to smaller heat transfer area and tube. On the other hand, the overall heat transfer coefficient and Nusselt numbers have larger rates at smaller tube diameter. In conclusion, the nominated tube diameter for FGAHE is the smaller diameter of 0.0127 m due to the high thermal performance.

scholarly journals Increasing the Thermal Efficiency of Double Tube Heat Exchangers by Using Nano Hybrid

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Mohamad Hosein Barzegar ◽  
Mohamad Fallahiyekta
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cold Water ◽  
Hybrid Nanoparticles ◽  
Hybrid Nanofluid ◽  
Twisted Tape ◽  
Overall Heat Transfer Coefficient ◽  
Turbulent Flow Regime ◽  
Double Pipe

In this study overall heat transfer in a double pipe heat exchanger fitted with twisted-tape elements and hybrid nanofluid were studied experimentally. Hybrid nanoparticles with a diameter of 20nm and a concentration of 1% (w/w) were prepared. The effects of temperature, mass flow rate, concentration of nanoparticles on the overall heat transfer coefficient and heat transfer changes in the turbulent flow regime were investigated. The results showed that when both of twisted tape and nanofluid have been used, heat transfer coefficient was about 40 percent higher than when they were not used. The experimental results also showed that 1% Al2O3/CuO nanofluid with twisted tape has slightly higher heat transfer when compared to 1% hybrid nanofluid without twisted tape. Neural networks used for modeling the system. The dependency of overall heat transfer coefficient of nanofluid (OHTCNF) on Reynolds number have depicted. The correlation coefficient for all data 0.98 is the successful prediction is shown. In this experimental work, nanoparticles were dispersed in hot current and cold water absorbed heat from hot nanofluid, so this system could be a good candidate for using in food industries, because at the end of this process there isn't any needs of extracting nanoparticles from the cold current. The heat transfer rate from the heating fluid was calculated by some known equations.

scholarly journals Analysis of the effect of ultrasonic vibration on nanofluid as coolant in engine radiator

2021 ◽  
Vol 5 (5 (113)) ◽  
pp. 6-13
Author(s):  
Sudarmadji Sudarmadji ◽  
Santoso Santoso ◽  
Sugeng Hadi Susilo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Fluid Flow ◽  
Transfer Coefficient ◽  
Ultrasonic Vibration ◽  
Flow Rate ◽  
Volume Concentration ◽  
Aluminum Oxide Nanoparticles ◽  
Particle Volume ◽  
Overall Heat Transfer Coefficient

The paper discusses the combined methods of increasing heat transfer, effects of adding nanofluids and ultrasonic vibration in the radiator using radiator coolant (RC) as a base fluid. The aim of the study is to determine the effect of nanoparticles in fluids (nanofluid) and ultrasonic vibration on the overall heat transfer coefficient in the radiator. Aluminum oxide nanoparticles of 20–50 nm in size produced by Zhejiang Ultrafine powder & Chemical Co, Ltd China were used, and the volume concentration of the nanoparticles varied from 0.25 %, 0.30 % and 0.35 %. By adjusting the fluid flow temperature of the radiator from 60 °C to 80 °C, the fluid flow rate varies from 7 to 11 lpm. The results showed that the addition of nanoparticles and ultrasonic vibration to the radiator coolant increases the overall heat transfer coefficient by 62.7 % at a flow rate of 10 liter per minute and temperature of 80 °C for 0.30 % particles volume concentration compared to pure RC without vibration. The effect of ultrasonic vibration on pure radiator coolant without vibration increases the overall heat transfer coefficient by 9.8 % from 385.3 W/m2·°C to 423.3 W/m2·°C at a flow rate of 9 liter per minute at a temperature of 70 °C. The presence of particles in the cooling fluid improves the overall heat transfer coefficient due to the effect of ultrasonic vibrations, nanofluids with a volume concentration of 0.25 % and 0.30 % increased about 10.1 % and 15.7 %, respectively, compared to no vibration. While, the effect of nanoparticles on pure radiator coolant at 70 °C enhanced the overall heat transfer coefficient by about 39.6 % at a particle volume concentration of 0.35 % compared to RC, which is 390.4 W/m2·°C to 545.1 W/m2·°C at 70 °C at a flow rate of 10 liter per minute

scholarly journals Mini Channel Evaporator as MAC Device for Laptop Cooling System

2020 ◽  
Vol 8 (5) ◽  
pp. 2993-2998
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Air Conditioning ◽  
Cooling System ◽  
Laptop Computer ◽  
Air Conditioning System ◽  
Overall Heat Transfer Coefficient ◽  
Flow Through ◽  
Cooling Methods

Laptop computers are known for their compact features which lead to overheating problems. Along with its being compact, laptop computer developers are going for more advance components to be able to run advance computer programs making the laptop do much more which also adds more to the overheating problems of the laptop. Overheated laptops will lead to slower laptop performances, laptop failures and even damaging its components. This problem leads to the development of laptop cooling methods, from fans and blowers and other cooling methods. This study aims to develop a cooling system which involves an air-conditioning system, a Mini Air Conditioning System (MAC System). The key to this study is the fabrication of three(3) mini channel evaporators which has different inner hydraulic diameters but of the same surface area with an overall size and which is smaller than a laptop battery pack. The evaporator for this study was made from a copper block that was fabricated to produce fins and a groove for the refrigerant to flow through the evaporator. The inner hydraulic diameters for the refrigerant to flow through are, 1mm, 2mm, and 3mm. The overall heat transfer coefficient would be determined for each evaporator size. The study showed that the most effective evaporator for cooling the laptop was that of the 3mm evaporator and that using the MAC system is an effective way of cooling a laptop computer. It lowered the temperature of the laptop by 10.65 K versus the setup with no cooler at all and 8.01 K with the setup with a plain cooler. The study also showed that the 3mm evaporator has the highest overall heat transfer coefficient with 73.129W/m2K with a mass flow rate of 0.039 kg/s.

scholarly journals Experimental investigation of two-phase thermosyphon heat exchanger charged with acetone

2018 ◽  
Vol 70 ◽  
pp. 02003
Author(s):  
Janusz T. Cieśliński ◽  
Maciej Fabrykiewicz
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Thermal Characteristics ◽  
Working Fluid ◽  
Shell Side ◽  
Two Phase ◽  
Overall Heat Transfer Coefficient ◽  
Working Liquid

This paper presents thermal characteristics of prototype of a two-phase thermosyphon heat exchanger (TPTHEx) charged with acetone as a working fluid. The TPTHEx consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. The tested TPTHEx operates in a vacuum. Therefore, the working liquid is boiled in temperatures ranging from 33°C to 62°C. The overall heat transfer coefficient (OHTC) of the tested TPTHEx was estimated by the use of the Wilson method and the modified Peclet equation. The results obtained indicate a superiority of water over acetone as a working fluid. Moreover, it was shown that having a lower pressure in the shell-side of TPTHEx results in a higher overall heat transfer coefficient. The Wilson method and the modified Peclet equation predict OHTC with satisfactory agreement.

A Method to Estimate Real-Time Energy Performance and Carbon Offsets in Residential Buildings

2010 ◽  
Author(s):  
Sergio Escobar ◽  
Jorge E. Gonza´lez ◽  
Adam Wong ◽  
Mark Aschheim
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Real Time ◽  
High Performance ◽  
Residential Buildings ◽  
Thermal Characteristics ◽  
Energy Performance ◽  
Carbon Offsets ◽  
Overall Heat Transfer Coefficient

A method is presented to determine energy performance of residential buildings. The method is based on an extended application of the degree-days basis to determine building thermal performance. The overall heat transfer coefficient and radiation shading factors are extracted from nightime and daytime readings of indoor and outdoor temperatures, solar radiation, and total energy usage of the building. It is shown that the overall heat transfer coefficient (thermal response) UA of the building is linear. Radiation shading factors can be represented as nonlinear functions of time. Application of the method to estimate real-time energy performance and carbon offsets of high performance buildings is discussed. The performance of the building is compared with an equivalent building with standard physical and thermal characteristics.

scholarly journals A numerical model and validation of phase change material integrated thermoelectric radiant cooling panel

2019 ◽  
Vol 111 ◽  
pp. 01001
Author(s):  
Hansol Lim ◽  
Hye-Jin Cho ◽  
Seong-Yong Cheon ◽  
Soo-Jin Lee ◽  
Jae-Weon Jeong
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Numerical Model ◽  
Surface Temperature ◽  
Phase Change ◽  
Transfer Coefficient ◽  
Phase Change Material ◽  
Overall Heat Transfer Coefficient ◽  
Radiant Cooling ◽  
Change Material

A phase change material based radiant cooling panel with thermoelectric module (PCM-TERCP) is proposed in this study. It consists of two aluminium panels, and phase change materials (PCMs) sandwiched between the two panels. Thermoelectric modules (TEMs) are attached to one of the aluminium panels, and heat sinks are attached to the top side of TEMs. PCM-TERCP is a thermal energy storage concept equipment, in which TEMs freeze the PCM during the night whose melting temperature is 16○C. Therefore, the radiant cooling panel can maintain a surface temperature of 16◦C without the operation of TEM during the day. Furthermore, it is necessary to design the PCM-TERCP in a way that it can maintain the panel surface temperature during the targeted operating time. Therefore, the numerical model was developed using finite difference method to evaluate the thermal behaviour of PCM-TERCP. Experiments were also conducted to validate the performance of the developed model. Using the developed model, the possible operation time was investigated to determine the overall heat transfer coefficient required between radiant cooling panel and TEM. Consequently, the results showed that a overall heat transfer coefficient of 394 W/m2K is required to maintain the surface temperature between 16○C to 18○C for a 3 hours operation.

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