Doctor of Philosophy

dissertationThis dissertation is aimed at explaining the development of the Thai economy from 1970 to 2010 from the Marxian and post-Keynesian perspectives: in particular, how the nonfarm rate of profit in Thailand interacts with its balance-of-payments constraint. The theoretical core of this dissertation, constructed in Chapter 2, is developed from the extended Thirlwall's law, in which capital flows, determined by the rate of profit, play a role to drive economic growth via balance-of-payments expansion, and from changes of the rate of profit due to changes in the organic composition of capital, determined by flows of foreign capitals. The model suggests that the dynamic interaction between the rate of profit and level of GDP generated from capitals flows most likely results in cyclical movements of these two variables. The rest of the dissertation consists of empirical works on the Thai economy. The nonfarm rate of profit in Thailand from 1970 to 2010 is measured in Chapter 3, and the decomposition analysis reveals the factors behind its fluctuations. The results show that the organic composition of capital and the output-capital ratio are the factors determining the nonfarm rate of profit. The model in Chapter 2, in order to explain cycles of an economy, requires two preliminary assumptions. First, the balance-of-payments-constrained growth models can explain its economic growth, and, second, the rate of profit determines the growth rate of capital flows. Chapter 4 proves these two assumptions by using the Thai data. To prove the first assumption, the full course of Thirlwall's law test is done, and it is found that the extended Thirlwall's law is better than the original Thirlwall's law in order to predict the Thai economic growth rates. For the second assumption, the ARDL bound testing in Chapter 3 determines the growth rate of capital flows. Chapter 5 puts together the nonfarm rate of profit and the GDP level generated from the extended Thirlwall's law. The empirical diagram behaves quite similarly to the theoretical diagram presented in Chapter 2, so the theoretical core of this dissertation can explain the Thai economic growth

On the Thermal Performance of the Vapor Chamber with Micro-channel for Unmixed Air Flow Cooling

Numerical and experimental results on the thermal performance of vapor chamber with and without micro-channel under constant heat flux are presented. The mathematical model of the vapor chamber is a two-phase closed chamber with wick sheet and a wick column. A finite volume method with structured uniform grid method system is applied to solve the model. Effects of micro-channel on the temperature distribution of the vapor chamber are considered. The results obtained from the model are verified with those from the measured data. The experimental tests are carried out and good agreement is obtained with the numerical results. These numerical results are useful for the design to improvement thermal performance of the vapor chamber and also diminished the expense and time of the real test

The Non-Farm Rate of Profit and the Thai Economic Development: 1970–2010

The article measures the non-farm profit rate in Thailand from 1970 to 2010. The shape of the profit rate suggests that the Thai economy can be differentiated into four phases. The decomposition analysis reveals that the organic composition of capital has greatly contributed to fluctuations of the profit rate, while the rate of capacity utilization and the capacity—capital ratio have positive impacts in three out of four phases. Meanwhile, the profit share and the rate of surplus value have just slight impacts on the profit rate. Furthermore, the article discusses that the capitalist class has always been a dominant class who could benefit from economic development, and the profit rate determines the growth rate of capital stock in Thailand

Thermal Performance Analysis of a Newly Designed Circular Firewood Boiling Salt Stove

Different biomass stoves are introduced and distributed among people living in rural and urban areas, especially in developing countries. For salt crystal production in Thailand’s rural north-eastern area, open fire stoves are used in domestic and small productive activities. Their thermal efficiency is very low for converting heat into utilization energy. A new stove with a circular configuration was designed and constructed to consider its thermal efficiency and economics, which were compared with those from a traditional and an improved traditional stove. The obtained thermal efficiency of the newly designed stove was 14.77% higher than that of the improved stove and 81.45% higher than that of the traditional stove. For the same initial saline volume, the final amounts of salt crystals and salt flowers obtained from the newly designed stove was higher compared with those obtained from the improved stove and the traditional stove, respectively, resulting in a 69.25% shorter payback period

Contrastive study of flow and heat transfer characteristics in a helically coiled tube under uniform heating and one-side heating

One-side heated helically coiled tubes, which are generally applied in various industrial applications such as the water cooled wall in power plant boilers though, have not been thoroughly studied. To investigate the flow and heat transfer characteristics in this case, numerical simulation of the flow in a helically coiled tube is performed under uniform and non-uniform (heating on the inner coil side wall) heat flux boundary conditions for both laminar and turbulent flows. Temperature distributions, secondary flow distributions, average Nusselt number variation with respect to Reynolds number and local Nusselt number along the periphery on the wall in the fully developed section are discussed contrastively under the two different heating conditions. It is found that the secondary flow distributions are hardly affected by changing heating method, however, a larger temperature gradient can be found for one-side heating condition. The average Nusselt numbers are close for laminar flow under the two heating methods, but one-side heating shows 7–10% lower average Nusselt numbers than uniform heating for turbulent flow, thus a new correlation of average Nusselt number for turbulent flow and one-side heating is proposed. Furthermore, a special point on the inner wall where the local Nusselt numbers are almost the same when carrying out different heating conditions in laminar and turbulent flows is found, which should be useful for measuring unknown parameters

Application of functionalized nanofluid in thermosyphon

A water-based functionalized nanofluid was made by surface functionalizing the ordinary silica nanoparticles. The functionalized nanofluid can keep long-term stability. and no sedimentation was observed. The functionalized nanofluid as the working fluid is applied in a thermosyphon to understand the effect of this special nanofluid on the thermal performance of the thermosyphon. The experiment was carried out under steady operating pressures. The same work was also explored for traditional nanofluid (consisting of water and the same silica nanoparticles without functionalization) for comparison. Results indicate that a porous deposition layer exists on the heated surface of the evaporator during the operating process using traditional nanofluid; however, no coating layer exists for functionalized nanofluid. Functionalized nanofluid can enhance the evaporating heat transfer coefficient, while it has generally no effect on the maximum heat flux. Traditional nanofluid deteriorates the evaporating heat transfer coefficient but enhances the maximum heat flux. The existence of the deposition layer affects mainly the thermal performance, and no meaningful nanofluid effect is found in the present study

Theoretical study of Oldroyd-b visco-elastic fluid flow through curved pipes with slip effects in polymer flow processing

The characteristics of the flow field of both viscous and viscoelastic fluids passing through a curved pipe with a Navier slip boundary condition have been investigated analytically in the present study. The Oldroyd-B constitutive equation is employed to simulate realistic transport of dilute polymeric solutions in curved channels. In order to linearize the momentum and constitutive equations, a perturbation method is used in which the ratio of radius of cross section to the radius of channel curvature is employed as the perturbation parameter. The intensity of secondary and main flows is mainly affected by the hoop stress and it is demonstrated in the present study that both the Weissenberg number (the ratio of elastic force to viscous force) and slip coefficient play major roles in determining the strengths of both flows. It is also shown that as a result of an increment in slip coefficient, the position of maximum velocity markedly migrates away from the pipe center towards the outer side of curvature. Furthermore, results corresponding to Navier slip scenarios exhibit non-uniform distributions in both the main and lateral components of velocity near the wall which can notably vary from the inner side of curvature to the outer side. The present solution is also important in polymeric flow processing systems because of experimental evidence indicating that the no-slip condition can fail for these flows, which is of relevance to chemical engineers

A review on the two-phase pressure drop characteristics in helically coiled tubes

Due to their compact design, ease of manufacture and enhanced heat transfer and fluid mixing properties, helically coiled tubes are widely used in a variety of industries and applications. In fact, helical tubes are the most popular from the family of coiled tube heat exchangers. This review summarises and critically reviews the studies reported in the pertinent literature on the pressure drop characteristics of two-phase flow in helically coiled tubes. The main findings and correlations for the frictional two-phase pressure drops due to: steam-water flow boiling, R-134a evaporation and condensation, air-water two-phase flow and nanofluid flows are reviewed. Therefore, the purpose of this study is to provide researchers in academia and industry with a practical summary of the relevant correlations and supporting theory for the calculation of the two-phase pressure drop in helically coiled tubes. A significant scope for further research was also identified in the fields of: air-water bubbly flow and nanofluid two phase and three-phase flows in helically coiled tubes