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

Due to the environment degradation and threats of the climate change, how to develop the technologies to use renewable energy and improve current energy systems to meet the increasing demand of human activities instead of using fossil fuels are amongst hot issues that being discussed nowadays. Due to the specific weather condition, district heating, which contains space heating and domestic hot water, is needed in Sweden. Solar energy is the most potential and environmental friendly energy resource. It can be utilized in many different aspects. The profitability of building solar heating plant for producing heat to supply the district heating in Sweden was discussed in the thesis. In order to achieve the result, central solar heating plant and solar combisystem were discussed. Information was collected from “Sciencedirect”, some related companies and institutions websites, and etc. Very few solar radiations are available during winter in Sweden, while the demands of district heating are the highest. During summer time, a lot of cities in Sweden can use the industrial waste heat to cover the district heating load, and in some cities where there is no industrial waste heat can operate biomass combined heat and power (CHP) plant to cover the heating load. Combined solar-biomass heating plant could improve the efficiency of biomass heating plant and reduce the unnecessary heat losses. Solar combisystem has a relatively high cost and complex system. The system which is able to supply some hot water for washing machine may have a good future, due to the possibility that the price of electricity in Sweden increases. Large-scale solar heating plants are less attractive in Sweden due to the existence of industrial waste heat and CHP plant that supplied by biomass. Combined solar-biomass heating plant would be a good system to build if there is no available industrial waste heat and biomass heating plant is used to supply the district heating. Due to the current electrical price and the cost of combisystem, it is not that attractive to build this system. In the coming future, if the transportation cost and the price of biomass itself become too high to make the CHP plant no longer cost effective, and the price of the electricity become high, the solar energy will make more contribution to the district heating in the coming future.

The concept of exergy is defined and applied to district heating systems. The influence from different reference state conditions and system boundaries are explained in some detail. The aim is to show the simplicity and value of using the concept of exergy when analyzing district heating processes. The exergy factor is introduced and applied for a number of Swedish and Danish district heating systems. This varies from 14.2% to 22.5% for Swedish district heating systems. The higher the exergy factor, the more the exergy losses in the passive conversion towards space heating. Large losses revealed in an exergy treatment of a process should be seen as a challenge to achieve technical improvements of the system.

In cooperate with Asko Cylinda we have developed a new heat system too short the process time and reduce the energy consume in a dishwasher and still have it too be a class AAA. The environment and quality is important for the company too still be the number one on the market, If they want too keep that position the product developed of new innovations will be very important. The systems we have developed are more effective and reduce energy up too 25 %. The process time is reduced too less than two hours, from the today two and half-hour. The solutions are too heat up the rinse water and the dishwater at the same time, with a new heating system and it make are solutions unique and effective. Its good for the dish and the environment. This will help the company too still be the number one on the market for household appliances.

In the last decades terms like Global Warming and Sustainable development have arisen. The anthropogenic green house gases emissions have raised the concentration of CO2 in the atmosphere to levels that might lead to a high increase in the average temperature in Earth. One of the most effective ways to fight against this phenomenon is to promote clean renewable energies. Among them, solar energy has the biggest developing potential and has proved to be an efficient and cost-effective energy source for different applications; one of them being the production of Domestic Hot Water and Space Heating. The aim of this Thesis is to study the possibilities to provide a single family house with hot water and space heating in an environmental friendly way. To do so, a solar system with biomass support will be designed for a single family house in northern Spain. The building has total energy demand of 20.5 MWh a year, of which 18 MWh correspond to space heating and 2.5 MWh to domestic hot water. The chosen solution for the building includes 12 solar collectors with a total area of 23.4 m2, a biomass boiler with a nominal power of 30 kW and a 32 kW oil boiler. Additionally, a radiant floor system was used as it perfectly adapts to the low temperature of the solar system. The result is an installation working with an 85% of renewable energies. This high share of renewable energy entails savings of 2,000 liters of oil a year, avoiding the emission of 4.5 tones of CO2 to the atmosphere every year. The economic calculations show that the pay back of the investment is 10 years with a Internal Rate of Return of 13%. Therefore, it can be said that, for this particular building and due to the governmental subsidies granted, solar energy is a cost effective alternative to provide the basic energy needs of a house.

In this thesis, we will investigate the degradation of the Low-Temperature-Polycrystalline-Silicon TFTs(LTPS TFTS) under the electrical stress. The devices are offer by Chi Mei Optoelectronics. The two mechanisms of the electrical stress are AC and DC stress. On the AC stress, there are some phenomena which cannot be completely explained by typical NBTI mechanism in the experiment. In addition to NBTI, we suggest that the self-heating effect might be involved, because the self-heating effect could rise channel temperature and cause the dissociation of the Si-H bonds at the poly-Si/SiO2 interface due to the Joule heating. We also compare pulse to give on the degradation difference of different place. On the DC stress, we show the stress drain voltage dependence of on-current and threshold voltage degradation, in which the stress gate voltage was fixed at -15V and stress time was 2154 s. The electric measurements of forward and reverse modes were employed to analyze the experimental data. The anomalous negative bias temperature instability degradation of poly-Si TFTs was investigated.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: John R. Howell. Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Jerold W. Jones. Vita. Includes bibliographical references. Available also from UMI Company.

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