Begell House Inc.
Heat Transfer Research
HTR
1064-2285
49
4
2018
HEAT TRANSFER CHARACTERISTIC FOR A LARGE-SCALE DOUBLE-DECK FLOATING ROOF OIL TANK
287-307
Jian
Zhao
Oil and Gas Storage and Transportation Department, Northeast Petroleum University, Daqing, P.R. China
Lixin
Wei
Oil and Gas Storage and Transportation Department, Northeast Petroleum University, Daqing,
P.R. China
Hang
Dong
Oil and Gas Storage and Transportation Department, Northeast Petroleum University, Daqing,
P.R. China
Hui
Ding
Oil and Gas Storage and Transportation Department, Northeast Petroleum University, Daqing,
P.R. China
Xinyang
Li
Oil and Gas Storage and Transportation Department, Northeast Petroleum University, Daqing,
P.R. China
The heat transfer characteristic for a double-deck floating roof oil tank was investigated based on the test of surface temperature and heat flow in working conditions. The profile of surface temperature on the roof generally appears an axial symmetry feature, dominated by the thickness of the roof and oil volatilization. The clapboard and truss enhance heat conduction which induces higher surface temperature in some local positions. The maximum temperature on the roof appears in the region between the weir plate and sidewall, while the lowest temperature region is the central part of the roof. Moreover, according to the profile of surface temperature, the sidewall is divided into two parts separated by the oil level. Based on the test data, nearly 70% of heat is lost through the roof, followed by the sidewall and bottom. The heat flow test reveals
an approximate one-dimensional characteristic of heat transfer through the roof. The value of the equivalent conductivity of the roof is from 2.63 W/m·K to 6.05 W/m·K while the average value is 4.44 W/m·K. The test result of sidewall reveals additional thermal resistance most likely caused by the wax precipitation layer which should be noted during the heat transfer calculation.
FORCED CONVECTION GREENHOUSE GROUNDNUT DRYING: AN EXPERIMENTAL STUDY
309-325
Ravinder
Sahdev
Assistant Professor
Mahesh
Kumar
Department of Mechanical Engineering, Guru Jambheshwar University of Sciences and Technology,
Hisar, 125001, India
Ashwani Kumar
Dhingra
Department of Mechanical Engineering, University Institute of Engineering and Technology,
Maharshi Dayanand University, Rohtak, 124001, India
In this study, the convective and evaporative heat transfer coefficients of groundnut were evaluated in a forced convection greenhouse drying (FCGHD) mode. The groundnuts were dried in the roof-type even span greenhouse with a floor area of 1.20 × 0.8 m2 in a forced mode in the climatic conditions of Rohtak, India (28°54'0"N 76°34'0"E). Three different wire
mesh trays of 0.15 × 0.25 m2 (Sample 1), 0.25 × 0.40 m2 (Sample 2), and 0.35 × 0.60 m2 (Sample 3) sizes were used to accommodate
a thin layer of groundnuts. Groundnuts were dried in the FCGHD mode till an optimum safe moisture storage
level of 8−10% was reached. The hourly experimental data were used to determine the values of experimental constants C and n in the Nusselt number expression by simple linear regression analysis and, consequently, the convective heat transfer coefficients (CHTC) were calculated. The value of CHTC was found to decrease with increase in the tray size. The average
value of the greenhouse efficiency was found to be 38.56%, 26.95%, and 31.99% for drying groundnut Samples 1, 2, and 3, respectively. The energy and exergy efficiencies were also evaluated and their values were observed to be 54.45%, 77.92%, and 65% and 2.57%, 1.01%, and 0.95% for drying groundnut Samples 1, 2, and 3 in the FCGHD mode, respectively. The experimental errors in terms of percent uncertainty were also evaluated. They were found to vary from 19.62% to 64.10%. The error bars for CHTC and evaporative heat transfer coefficient (EHTC) are also shown for groundnut drying under FCGHD conditions.
NUMERICAL MODELING OF HEAT AND MASS TRANSFERS UNDER SOLAR DRYING OF SEWAGE SLUDGE
327-348
Nidhal Ben
Hassine
Laboratoire de Mathématiques et Physique, University of de Perpignan Via Domitia, 52 Paul
Alduy Ave., 66860 Perpignan Cedex 9, France; Laboratoire d'Energétique et Transferts Thermique et Massique, Faculty of Science of Bizerte,
University of Carthage, Jarzouna 7021, Tunisia
Xavier
Chesneau
Laboratoire de Mathématiques et Physique LAMPS, Université de Perpignan via Domitia, 52
Avenue Paul Alduy, 66860 Perpignan Cedex 9, France
Ali Hatem
Laatar
LETTM, Department of Physics, Faculty of Sciences of Tunis, Tunis El Manar University, 1060 Tunis, Tunisia; Department of Physics, Faculty of Sciences of Bizerte, University of the 7th November at Carthage, 7021 Jarzouna-Bizerte, Tunisia; Department of Physics, Faculty of Sciences of Tabuk, Tabuk University 71491, Saudi Arabia
The drying of sewage sludge is a current environmental problem, not sufficiently described in the literature. Hence, the aim of this work is a numerical study of heat and mass transfer under solar drying of residual sludge. This sludge is assimilated to a porous medium and exposed to a forced convection laminar flow within a horizontal channel. The processes of transfer in the channel and in the porous medium are respectively described by the classical equations of forced convection and of the Darcy–Brinkman–Forchheimer model. The implicit finite difference method is used to discretize the governing differential equation system. The algebraic systems obtained are solved using the Gauss, Thomas, and Gauss–Seidel algorithms. To determine the drying rate, we associate a drying kinetics model. We particularly studied the effects of solar radiation intensity
and ambient air temperature on the space–time evolution of temperature, velocity, and mass traction at the ambient
air–porous medium interface. Moreover, the evolutions of Nusselt and Sherwood numbers are represented to characterize
the processes of transfer at the sludge surface. This work is completed by a drying kinetics study. Indeed, we represent the space–time evolution of the drying rate and water content.
PERFORMANCE ANALYSIS OF DOUBLE-LAYER MICROCHANNEL HEAT SINK WITH VARIOUS MICROCHANNEL SHAPES
349-368
Kishor
Kulkarni
Department of Mechanical Engineering, Inha University, 100 Inha-Ro, Nam-Gu, Incheon 22212,
Republic of Korea
Aatif Ali
Khan
Department of Mechanical Engineering, Inha University, 100 Inha-Ro, Nam-Gu, Incheon 22212,
Republic of Korea
Kwang-Yong
Kim
Department of Mechanical Engineering, Inha University, 100, Inha-Ro, Nam-Gu, Incheon, 22212,
Republic of Korea
The thermal hydraulic performance of a double-layer microchannel heat sink was analyzed with a variety of channel shapes using three-dimensional Navier–Stokes equations in a range of Reynolds numbers from 160 to 850. Parallel and counterflow
arrangements of double-layer microchannels and seven cross-sectional shapes of microchannels (boot, diamond, hexagonal, pentagonal, rectangular, rectangular wedge, and triangular) were tested in this work. The temperature, Nusselt number, thermal resistance, and pumping power were obtained for each channel shape and arrangement using conjugate heat transfer analysis. Among the tested microchannel shapes, the rectangular wedge shape showed the best thermal performance with the lowest thermal resistance and also with the greatest pumping power. The counterflow arrangement showed better thermal performance with a similar pumping power than the parallel flow arrangement for all the channel shapes.
DUAL-PHASE-LAG HEAT CONDUCTION IN AN FG HOLLOW SPHERE: EFFECT OF THERMAL PULSE TYPE AND LOCATION OF A HEAT SOURCE
369-384
Majid
Bakhtiari
Department of Mechanical Engineering, Iran University of Science and Technology, Narmak,
Tehran 16844, Iran
Kamran
Daneshjou
Department of Mechanical Engineering, Iran University of Science and Technology, Narmak,
Tehran 16844, Iran
Hossein
Parsania
Department of Mechanical Engineering, Iran University of Science and Technology, Narmak,
Tehran 16844, Iran
The purpose of this paper is to introduce a new mathematical model to solve the heat conduction equation based on the
Dual-Phase-Lag (DPL) theory for investigation of temperature field affected by thermal pulse and heat source location on an FG hollow sphere. This new model, named augmented state space method, based on the laminate approximation theory
in the Laplace domain, can obtain a transient solution, and then the results obtained are converted into the time domain by applying the numerical Laplace transform inversion with consideration of Gibb's phenomenon. Numerical analyses show
the effects of thermal pulse and heat source location and phase lags ratio as boundary conditions on the distribution of temperature on an FG sphere. It is clear that the thermal pulse functions and location of a heat source have different effects on the temperature distribution. In addition, by changing the phase lags ratios, the temperature distribution on a radius and in time history are obtained. Eventually, the results obtained by this method are verified by using some problems available in the literature.