A Study on Control of Heater Power and Heating Time for Thermoforming

Zhen-Zhe Li,Guang Ma,Dong-Ji Xuan,Seoung-Yun Seol,Yun-De Shen 한국정밀공학회 2010 International Journal of Precision Engineering and Vol. No.

Obtaining a uniform thickness of the final product using thermoforming is difficult, and the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper, the time-dependent temperature distribution of the total sheets in the storing stage was studied because the temperature after the storing stage is the initial temperature of the heating process. An analytic solution for simulating the storing stage was derived. Using the solved analytic solution, the time-dependent temperature distribution of the total sheets was found out under the condition of assuming that the temperature-dependent specific heat of the ABS sheets was a certain constant value. Finally, the control method for a successful thermoforming using the heater power or heating time was researched in order to improve the quality of the final products. The results show that the satisfied temperature distribution can be obtained by adjusting the heater power or heating time. The method for analysis in this study will be used to improve the quality of the final products.

Optimal Design for Cooling System of Batteries Using DOE and RSM

Zhen-Zhe Li,Yun-De Shen,Tai-Hong Cheng,Dong-Ji Xuan,Ming Ren,Gui-Ying Shen 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

A hybrid power composed of fuel cell and batteries has become the good strategy for HEV. On the contrary, the produced heat of batteries can affect to the total performance of HEV significantly. In this study, simulation methods with optimization were developed for obtaining the high performance cooling system of batteries. At first, a numerical method for obtaining the temperature distribution of batteries was developed by using CFD. In the following step, several parameters were investigated for selecting design variables with the important effect on the performance of the cooling system of batteries. Finally, an optimization method based on DOE and RSM was obtained through a real optimal design. There was 21.1% reduction on the view of the root mean square temperature between batteries as shown in the optimization result. The developed analysis with optimization can be used to improve the performance of the cooling system of batteries, and these works have made the theoretical basis for simulation and optimization of the cooling system of batteries.

A study on cooling efficiency using 1-d analysis code suitable for cooling system of thermoforming

Zhen-Zhe Li,호광수,Dong-Ji Xuan,설승윤 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.3

Thermoforming is one of the most versatile and economical processes available for polymer products, but cycle time and production cost must be continuously reduced in order to improve the competitive power of products. In this study, water spray cooling was simulated to apply to a cooling system instead of compressed air cooling in order to shorten the cycle time and reduce the cost of compressed air used in the cooling process. At first, cooling time using compressed air was predicted in order to check the state of mass production. In the following step, the ratio of removed energy by air cooling or water spray cooling among the total removed energy was found by using 1-D analysis code of the cooling system under the condition of checking the possibility of conversion from 2-D to 1-D problem. The analysis results using water spray cooling show that cycle time can be reduced because of high cooling efficiency of water spray, and cost of production caused by using compressed air can be reduced by decreasing the amount of the used compressed air. The 1-D analysis code can be widely used in the design of a thermoforming cooling system, and parameters of the thermoforming process can be modified based on the recommended data suitable for a cooling system of thermoforming.

Optimization for Cooling System of Batteries Having Porous Material Using Design of Experiments

Zhen-Zhe Li,Dong-Ji Xuan,Yong Li,Yun-De Shen 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

A hybrid power composed of fuel cell and batteries has become the reasonable strategy for hybrid electric vehicles. On the contrary,the produced heat by batteries can affect the total performance of hybrid electric vehicles significantly. In this paper, analysis methodsand optimization strategy were constructed for obtaining the high performance cooling system for batteries having porous material. At first, a numerical method for obtaining the temperature distribution of battery pack including porous material was developed byusing CFD technique. In the following step, the cooling systems for batteries with porous material or not were compared for showingthe merit of the cooling system for batteries having porous material. Ultimately, an optimization strategy based on D-optimal DOEmethod was obtained through a real optimal design process. There was 13.3% reduction on the view of the root mean squaretemperature between batteries compared with the original cooling system for batteries as shown in the optimization result. Theconstructed analysis method and optimization strategy can be used to improve the performance of the cooling system for batteries,and these works have made the theoretical basis for simulation and optimization of the cooling system for batteries.

Time-dependent Optimal Heater Control in Thermoforming Preheating Using Dual Optimization Steps

Zhen-Zhe Li,Kwang-Su Heo,Seoug-Yun Seol 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.4

Thermoforming is one of the most versatile and economical processes available for shaping polymer products, but obtaining a uniform thickness of the final product using this method is difficult. Heater power adjustment is very important because the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper; the steady-state optimum distribution of heater power is first ascertained by a numerical optimization to obtain a uniform sheet temperature. The time-dependent optimal heater input is then determined to decrease the temperature difference through the direction of the thickness using the response surface method and the D-optimal method. The optimal results show that the time-dependent optimum heater power distribution gives an acceptable uniform sheet temperature in the forming temperature range by the end of the heating process.

Time-dependent Optimal Heater Control in Thermoforming Preheating Using Dual Optimization Steps

Li, Zhen-Zhe,Heo, Kwang-Su,Seol, Seoung-Yun Korean Society for Precision Engineering 2008 International Journal of Precision Engineering and Vol.9 No.4

Thermoforming is one of the most versatile and economical processes available for shaping polymer products, but obtaining a uniform thickness of the final product using this method is difficult. Heater power adjustment is very important because the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper, the steady-state optimum distribution of heater power is first ascertained by a numerical optimization to obtain a uniform sheet temperature. The time-dependent optimal heater input is then determined to decrease the temperature difference through the direction of the thickness using the response surface method and the D-optimal method. The optimal results show that the time-dependent optimum heater power distribution gives an acceptable uniform sheet temperature in the forming temperature range by the end of the heating process.

Predictive Offloading Method and Framework Design Model for Efficient Mobile Cloud Computing

Piao, Zhen Zhe,Kim, Soo Dong Science and Engineering Research Support Society 2017 International Journal of Control and Automation Vol.10 No.10

전산 열해석 DB 를 이용한 초고온 진공로 최적설계

리진철(Zhen-Zhe Li),이재우(Jae-Woo Lee),이창진(Chang-Jin Lee),최인석(In-Seok Choi) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

Optimization study has been carried out to design an energy efficient, high temperature vacuum furnace which satisfies users' design requirements. First of all, the unsteady temperature distribution and the working zone results have been compared with the steady state results to validate the suitability of using steady state results when constructing the thermal analysis DB. In order to check the accuracy of the constructed thermal analysis DB, the interpolated results using constructed thermal analysis DB have been compared with computational results and experimental results. For this design problem, total heat flux is selected as the objective function, and the geometry of vacuum furnace including thickness of insulator, heat zone sizes and the interval between heater and insulator are the design variables, and the working zone sizes and the wall temperature are imposed as the design constraints. Finally, with negligible computational cost a high temperature vacuum furnace whick has 40~60% reduction in the total heat flux is designed using constructed thermal analysis DB.

Time-Dependent Optimal Heater Control Using Finite Difference Method

Li Zhen-Zhe,Heo Kwang-Su,Choi Jun-Hoo,Seol Seoung-Yun 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

Thermoforming is one of the most versatile and economical process to produce polymer products. The drawback of thermoforming is difficult to control thickness of final products. Temperature distribution affects the thickness distribution of final products, but temperature difference between surface and center of sheet is difficult to decrease because of low thermal conductivity of ABS material. In order to decrease temperature difference between surface and center, heating profile must be expressed as exponential function form. In this study, Finite Difference Method was used to find out the coefficients of optimal heating profiles. Through investigation, the optimal results using Finite Difference Method show that temperature difference between surface and center of sheet can be remarkably minimized with satisfying Temperature of Forming Window.

열해석을 통한 스팀 발생기구 성능 개선에 대한 연구

리진철(Li Zhen-Zhe),허광수(Heo Kwang-Su),최준호(Choi Jun-Hoo),설승윤(Seol Seoung-Yun) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Steam generation mechanism is the key technology of domestic steam cleaner. Not only weight and price of steam cleaner but also the performance of steam generation mechanism must be considered to improve the competitive power of the products. In order to find out the mechanism which can be used to improve the performance of steam generator, the process of steam generation was studied at first. In the following step, possibility of control, safety of mechanism and etc were compared about the two candidated steam generation mechanism. Finally, the merit and drawback of each mechanism were summarized.