Thermal Compression Process Research Articles

Thermodynamic design and parametric study of MED-TVC

The present work summarizes parametric optimization technique of multi effect desalination with thermal vapor compression (MED-TVC) process to increase gain output ratio (GOR) value. In order to increase GOR value, a simulation model of MED-TVC system is presented. This simulation can provide engineers a cost-effective tool for thermodynamic design, development and optimization of the thermal desalination plants. Also, a mathematical model has been developed which can predict the effect of all parameters on total capacity, performance ratio of the system, temperature difference between effects and pressure on each effect under design and operating conditions. The transient nature of temperature during the seasons is modeled by ordinary differential equations based on mass and energy balance. An actual system is used to compare GOR values of theoretical and experimental results. In this paper, it is shown that by means of parametric study, the computer simulation tool developed will help designers to achieve the best setting for desalination process to increase GOR value and minimize the energy consumption. The comparison between the simulation results, with experimental data well proves the validity of parametric study.

Assessment of energy requirement for water production at dual-purpose plants in China

With the fast development of the economy and huge amount of population, fresh water shortages have become very serious in China, especially in northern coastal cities where China's population and economy are concentrated. The coal-fired power plant integrated with low-temperature multi-effect distillation (LT–MED) is a viable way to solve or eliminate the problems in China as the coal-fired power plant dominates in power industry and LT–MED has technical advantages in using low temperature heat resources over other desalination technologies. An accurate assessment on energy requirement of water production is of great importance in dual-purpose plants since the cost of energy requirement accounts for the foremost part of the water production cost. This paper presents an economic analysis of the energy cost of water production for dual-purpose plants by the equivalent enthalpy drop theory (EEDT) and the off-design analytical theory on steam turbines. EEDT that is proven to be an effective method for partial quantitative analysis can be used to accurately calculate both the energy requirement of water production and the economic influence of extraction steam on steam turbines. By solving the matrix models of EEDT, electricityequivalent consumption rate (EECR) for water production and reduced steam turbine efficiency ratio were analyzed at off-design conditions for LT–MED combined with thermal vapor compression process (TVC) process. The results indicate that EECR is more accurate to be used to evaluate the economics of the desalination process than GOR that is widely used. They also show that EECR that is the function of the equivalent enthalpy drop, the share of the extraction for heating the desalination process, and GOR reflects the real work ability of extraction. Besides, it is seen that the specific fuel cost for water production is low compared with that of reverse osmosis. It is concluded that the coal-fired power plant integrated with LT–MED is an economical and suitable way to resolve the water shortages in northern coastal zone of China.

DENSIFIED RADIATA PINE FOR STRUCTURAL COMPOSITES

A novel wood-based composite has been developed for use in structural applications. The process was designed to utilize rapidly-grown, low density, wood species. Plantation grown radiata pine is particularly well suited to this process. This is a laminated composite, where the lamina may be comprised of various materials, some of which have been treated with the viscoelastic thermal compression (VTC) process. The VTC process increases the density of wood, without causing fractures in the cell wall, thus increasing strength and stiffness of the wood material. The process may be applied to veneer, sawn wood, or strand composites. The VTC lamina is then bonded to other lamina to produce the final product. The strength and stiffness of this VTC composite exceeds any wood-based composite that is currently on the market. For example, modulus of elasticity in bending of over 20 GPa is easily obtainable.