Production of surimi represents a potential utilization of a number of low-valued fish species, one of which, Pacific whiting, represents the largest biomass off the West Coast of the United States. However, a protease enzyme softens the fish flesh in Pacific whiting and limits the expansion of surimi production. Many studies have demonstrated the importance of time and temperature in minimizing the texture softening. An optimal design of the surimi seafood process is possible only when an accurate prediction of the time-varying temperature distribution throughout the surimi product can be obtained. This provides a measure of the heating rate and the extent of thermal processing. Such a prediction necessitates a study of the surface heat transfer coefficient which is one of the most important parameters for the heat transfer analysis. Associated with automated-machinery processing of surimi seafoods, a full understanding of the heat transfer coefficient (h) is especially important because high-quality surimi products using Pacific whiting only can be obtained through rapid and controlled heating. This study was intended to determine transient surface heat transfer coefficients in a steam heating environment, simulating the widely-used steam heating of thin-sheet surimi paste in the seafood industry. In determining the heat transfer coefficient, many different methods have been used including the inverse calculation method, the lumped mass method and the heat flux method. This study employed all three to measure and model the heat transfer coefficient (h) under similar steam conditions. A comparative evaluation was made to define the best method and model for the h determination. The inverse calculation method produced an h model which, when applied to a heat transfer analysis, provided the best agreement between predicted and experimental temperature profiles at three locations in surimi paste during a 1000-sec cooking period. The lumped mass method overestimated the heat transfer coefficients to food; the heat flux method gave inconsistent measurements. It is a classic inverse problem to estimate surface heat transfer coefficients from temperature measurements inside a product, a procedure which involves solution of the inverse heat conduction problem and parameter optimization. A whole domain function specification procedure was developed for the inverse calculation method. This procedure simulates heat transfer coefficients as specified functions by estimating all the unknown parameters in the functions over the total time interval. A nonlinear regression computer program was written for the inverse calculation of surface heat transfer coefficients, incorporating the implict Crank-Nicolson scheme for the finite-difference formulation of the one-dimensional heat conduction problem and the downhill simplex method for parameter optimization. This inverse calculation method provided relatively accurate models of the surface heat transfer coefficient. / Graduation date: 1997

Graduation date: 1995

Thesis (M.S.)--Ohio State University, 1983. / Includes bibliographical references (leaves 84-85). Available online via OhioLINK's ETD Center

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--School of Computing and Engineering and Dept. of Mathematics and Statistics. University of Missouri--Kansas City, 2005. / "A dissertation in engineering and mathematics." Advisor: Bryan R. Becker. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed March 12, 2007. Includes bibliographical references (leaves 216-220). Online version of the print edition.

Colloidal solvents, containing dispersed nanometer (~1-100 nm) sized particles, are categorized as nanofluids. With the growing heat loads in engineering systems that exceed the current technological limits, nanofluids are considered as an attractive option for more efficient heat removal for thermal management applications. Recent results reported in the literature show that the thermo-physical properties of coolants are enhanced considerably when seeded with very minute concentrations of nanoparticles. Hence, nanofluids research has provoked interest in thermal management applications. The convective heat transfer characteristics of nanofluids are reported in this study. Exfoliated graphite nanoparticles were dispersed in poly-alpha-olefin (PAO) at concentrations of 0.3% and 0.6% (by weight). The heat flux into a convective cooling apparatus was monitored and the results for nanofluid and the base fluid are presented. Thermo-physical properties of the nanofluid were measured and compared with the base fluid. The thermo-physical properties of the fluid are observed to increase with the addition of the nanoparticles. The specific heat of nanofluid was increased by ~50% compared to PAO. The thermal diffusivity was enhanced by ~400% compared to PAO. The viscosity of the nanofluid was enhanced by 10-1000 times compared to PAO. The viscosity of the nanofluid was observed to increase with temperature while the viscosity of PAO decreases with temperature. The convective heat flux was enhanced by the nanofluids by up to ~8 % for experiments performed at different heat inputs. The experimental results show that the convective heat transfer enhancement potentially results from the precipitation of nanoparticles on the heated surface and results in enhanced heat transfer surfaces (“nano-fins”).

Experiments and numerical predictions were conducted to study heat (mass) transfer characteristics in a two-pass trapezoidal channel simulating the cooling passage of a gas turbine blade. Three different rib configurations were tested for the air entering the smaller cross section of the trapezoidal channel as well as the larger cross section of the trapezoidal channel at four different Reynolds numbers of 9,400, 16,800, 31,800, and 57,200. (+) 60º ribs, (–) 60º ribs and 60º V-shaped ribs were attached on both the top and bottom walls in parallel sequence. A naphthalene sublimation technique was used, and the heat and mass transfer analogy was applied to convert the mass transfer coefficients to heat transfer coefficients. Numerical predictions of three-dimensional flow and heat transfer also were performed for the trapezoidal channel with and without 90º ribs tested by Lee et al. (2007). Reynolds stress turbulence model (RSM) in the FLUENT CFD code was used to calculate the heat transfer coefficients and flow fields at Re = 31,800. The results showed that the combined effects of the rib angle, rib orientation, and the sharp 180° turn significantly affected the heat (mass) transfer distributions. The secondary flows induced by the sharp 180° turn and the angled or V-shaped ribs played a very prominent role in heat (mass) transfer enhancements. The heat (mass) transfer enhancements and the pressure drops across the turn for 60° V-shaped ribs had the highest values, then came the case of (+) 60° ribs, and the heat (mass) transfer enhancements and the friction factor ratios for (–) 60º ribs was the lowest. However, comparing (–) 60º ribs with the 90º ribs, (–) 60º ribs produced higher heat (mass) transfer enhancements than the 90º ribs, as results of the secondary flow induced by the (–) 60º ribs. The overall average heat (mass) transfer for the larger inlet cases was always higher than that for the smaller inlet cases in the ribbed trapezoidal channel. Considering the thermal performance comparisons of the (+) 60° ribs, the (–) 60º ribs, and 60° V-shaped ribs for the smaller inlet cases, the highest thermal performance was produced by the (–) 60º ribs, and the 60° V-shaped ribs and the (+) 60° ribs had almost the same levels of the thermal performance since the 60° V-shaped ribs produced the highest heat (mass) transfer enhancement but also produced highest pressure drops. For the larger inlet cases, the (+) 60° ribs produced the highest values, then came the case of the 60° V-shaped ribs, and the thermal performance for the (–) 60º ribs was the lowest. The Reynolds stress model (RSM) showed well flow fields and heat transfer distributions but underpredicted average Nusselt number ratios.

The window insulation always plays an important role in building design and thermal comfort, it is one of the main parts needed to be optimized in building envelop. Window insulation is a basic element which can decide the insulation capacity. The large heat loss from the window is the main part of wasting energy, and simultaneously, there is also difficult to explore the new energy source and to improve the current heat generation device efficiency in this energy crisis century. Therefore, building a proper insulated window system is a good approach to keep an acceptable indoor climate as well as to reduce energy use and negative climate effects. On the other hand, there are amounts of old houses and poorly design houses all over the world either in a well developed country or a developing country. Therefore it can form a better atmosphere to optimize the window worldwide. The aim of the thesis is telling the reader what kind of optimization can be done to get better window insulation. This thesis starts with a briefly introduction to give the basic knowledge of heat loss from windows, and then shows the heat loss level in comparison with other parts of building. Afterwards it gives the optimization strategy to make good window glazing and window frames. For frame design, the hollow frame material property and the benefits of insulants filling window system are described. There are still some problems which exist for the energy efficient windows, such as condensation problem. The thesis also shows this kind of problem and the solution approach.

Graduation date: 1990

Water-source and ice-maker heat pumps share many characteristics. However, each presents different technical difficulties that have prevented them from being used more widely. In a water-source heat pump a very important consideration is to reduce water consumption, while in an ice-maker heat pump a major concern is to reduce the number of deicing cycles while keeping a high performance. Previous research by this author has indicated that the use of the flow reversal method (reversing periodically the water flow direction in the evaporator) has the effect of partly deicing the evaporator, reducing pressure drop and enhancing heat transfer. This thesis shows the development and application of analytical and numerical models to study the effect of different evaporator parameters on heat pump efficiency, as well as the possible advantages of using the flow reversal method in a water-source or ice-maker heat pump. The conclusion reached from these studies is that periodic water flow reversals inside an evaporator with freezing help improve the performance of a heat pump system in two different ways. First, periodic water flow direction reversals serve to enhance heat transfer in the evaporator. Second, reversing the water flow direction also delays ice blockage in the evaporator, or totally prevents blockage from happening. Delaying ice blockage represents a substantial improvement for ice-maker heat pumps, since these may then operate for a longer time without deicing. Preventing ice blockage represents a substantial improvement for water-source heat pumps, since these may then operate at lower water flow rates. Suggestions for future work include further testing of the flow reversal method for different evaporator geometries, as well as an experimental evaluation of the flow reversal method. / Graduation date: 1990