scholarly journals Preparation and Investigation of heat transfer rate by using MgO-nanofluid in pipe-in-pipe Heat Exchanger

Author(s):  
Anoop Kumar
2021 ◽  
Vol 34 (02) ◽  
Author(s):  
Mohammad Sikindar Baba ◽  
◽  
Oddarapu Kalyani ◽  

SINERGI ◽  
2020 ◽  
Vol 25 (1) ◽  
pp. 51
Author(s):  
Sudiono Sudiono ◽  
Rita Sundari ◽  
Rini Anggraini

This preliminary investigation studied the effect of circular turbulator vortex generator on heat transfer rate and pressure drop in a circular channel countercurrent double pipe heat exchanger with water working fluid. Increasing the number of circular turbulator yielded increasing heat transfer rate and pressure drop. The problem generated when increased pressure drop occurred in relation to more energy consumption of the water pumping system. Therefore, optimization in circular turbulator number is necessary to minimize the pressure drop about distance length between circular turbulator, tube diameter and thickness, type of material and crystal lattice, as well as the geometrical shape of fluid passage (circular or square). This study applied PVC outer tube and copper alloy inner tube, as well as fiberglass circular turbulator. The optimum results showed that seven parts of circular turbulator increasing heat transfer rate by 30% and pressure drop by 80% compared to that passage in the absence of circular turbulator at cool water debit of 7 L/min.


2021 ◽  
Vol 1973 (1) ◽  
pp. 012113
Author(s):  
Zomorrod Ahmed Salman ◽  
Zena Khalefa Kadhim ◽  
Kamil Abdulhussein khalaf ◽  
Hassanein Ali Kamil

2013 ◽  
Vol 284-287 ◽  
pp. 908-914
Author(s):  
King Leung Wong ◽  
Wen Lih Chen ◽  
Li Wen Po

Log mean temperature difference (LMTD) method neglecting the influence of heat radiation is conventionally used to calculate the total heat transfer rate of heat exchangers. From recent investigation of a single-pipe heat exchanger in some practical situations, it is found that the total heat transfer rate error of single-pipe heat exchanger obtained by LMTD method is up to 40% in the situation of oxidized metal heat exchanger with higher surface emissivity located in ambient air with low heat convection coefficient. A log mean heat transfer rate (LMHTR) method considering heat radiation has been developed to calculate the total heat transfer rate of a single-pipe heat exchanger and more accurate results can be achieved. It is also found in the present investigation that LMTD method is also not suitable to apply to non-insulated double-pipe heat exchangers and a more accurate LMHTR method considering heat radiation is developed to obtain the more reasonable results.


2006 ◽  
Vol 129 (3) ◽  
pp. 265-272 ◽  
Author(s):  
J. R. Balikowski ◽  
J. C. Mollendorf

Phase change materials (PCMs) are used in applications where temperature regulation is important because they absorb and release a large amount of energy at a fixed temperature. In the experimental part of this investigation, PCM was placed in the annular region of a double-pipe heat exchanger with water circulated in the inside pipe. Experiments were performed in which the PCM would absorb (charge) and then release (discharge) energy at various temperatures and water flows. Two materials, Climsel 28 (C28) by Climator and microencapsulated Thermasorb 83 (TY83) by Outlast Technologies, were each tested in smooth and spined annuli to observe which configuration facilitated heat transfer. The latent heats and thermal conductivities of C28 and TY83 are 126kJ∕kg and 186kJ∕kg and 0.6W∕m∕°C and 0.15W∕m∕°C, respectively. The experimental data were analyzed to verify which PCM transferred more heat. The effect of different water flow rates on the heat transfer rate was also examined. In the theoretical part of this investigation, heat transfer theory was applied to C28 in the smooth-piped heat exchanger in order to better understand the phase change process. The presence of spined fins in the phase change material accelerated charging and discharging due to increased fin contact with the outer layers of the PCM. The spined heat exchanger charged and discharged in 180min and 120min, respectively, whereas the temperature in the smooth heat exchanger remained below the fully charged/fully discharged asymptote by about 3°C and thus failed to fully charge or fully discharge. Also, higher water flows increased heat transfer between the PCM and water. TY83 in the spined heat exchanger transferred more heat and did it faster than C28 in the spined heat exchanger. The heat transfer rate from the water to TY83 while charging was 25% greater during the transient period than in C28. While discharging, the heat transfer from TY83 to the water was about 20% greater than in C28. There was generally good agreement (±1.5°C) between theory and experimental data of C28 in the smooth-piped heat exchanger in terms of the trends of the temperature responses. The differences are expected to be a result of approximations in boundary conditions and uncertainties in how the temperature variation of the specific heat is formulated.


2013 ◽  
Vol 448-453 ◽  
pp. 3259-3269
Author(s):  
Zhi Wei Li ◽  
Hong Zhou He ◽  
Huang Huang Zhuang

The characteristics of the external heat exchanger (EHE) for a 4 MWth circulation fluidized bed combustor were studied in the present paper. The length, width and height of EHE were 1.5 m, 0.8 m and 9 m, respectively. The circulating ash flow passing the heating surface bed could be controlled by adjusting the fluidizing air flow and the heating transferred from the circulating ash to the cooling water. The ash flow rate passing through the heat transfer bed was from 0.4 to 2.2 kg/s. The ash average temperature was from 500 to 750 °C. And the heat transfer rate between the ash and the cooling water was between 150 and 300 W/(m2·°C). The relationships among the circulating ash temperature, the heat transfer, heat transfer rate, the heat transfer coefficient and the circulating ash flow passing through the heating exchange cell were also presented and could be used for further commercial EHE design.


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