Lerdlekha Tanachaikhan

Design of Capacitive Sensor for Concentration Measurement

This paper presents the analysis of ideal equivalent circuit of the developed concentration sensor probe for chemical solutions by regarding to reasonable costs and reliability of device. The designed sensor probe consists of 2 parallel electrode plates that are coated by Nylon with 0.4 mm thick and mounted together by Resin with 2.5 mm of gap (0.09 times greater than electrode width). Any capacity changes will be compared with the electric circuit that is obtained from the Good Will R-L-C standard instrument, model CTR, at the frequency extending from 100 Hz to 2 kHz. From the experiments, it was found that the sensor designed for ethyl alcohol solution within concentration of 5% to 95% and 10% concentration interval, at room temperature of 23 degC and frequency of 100 Hz, can provide the results with high linearity as well as high resolution of capacity change which is 2 pF per 1% of concentration

Subsidence monitoring system for industrial machines based on magnetic field method

This study presents the design of subsidence monitoring system for industrial machine alignment based on magnetic field method. The system was developed to demonstrate the level of land subsidence in the area of the industrial machine located. A computer was used to collect the data and to display the angles of subsidence over operation period. The measurement module consists of two thin-and-curve permanent magnets (10 mm × 41.5 mm × 1.5 mm) with the outer radius of 24 mm, the curve angle of 120 degree, and the maximum magnetic density of 0.23 Tesla. The gap between these two magnets was 12 mm to generate the magnetic tension force. The sensing module was Hall Generator placed perpendicularly to the magnetic fluxes which can generate the output voltage as a function of subsidence angle and magnetic density on X axis and Z (vertical) axis with the resolution of 100 mV per degree. There were two ranges of measurement according to the angle resolution: -20 to 20 degree at 1 degree of resolution per step and -6 to 6 degree at 0.05 degree of resolution per step.

Application of parallel ladder technique for purging oil residual inside the copper pipe

In iron pipe industry, one of the most important problems in manufacturing processes is the great amount of oil residual in copper pipe. This problem can be affected the use of copper pipe further such as difficulty in pipe soldering, pipe rust and leakage. This study aims to demonstrate the use of parallel ladder technique, the simple process with low additional costs, to purge out liquid residual in the pipe after ironing. This technique can improve the efficiency of the manufacturing process as well as increase the quality of the product. Nitrogen was applied in this process with the step-increasing pressure of 0, 5, 10, and 15 Bar. This supplied pressure levels are a function of time which depend on the length of pipe. Nitrogen with specified pressure levels were controlled by 3 sets of control valves which were parallelly arranged. For efficiency test, two sizes of copper pipe which are commonly used for producing coil of air conditioner were used as a case study, Pipe A (diameter of 7.29 mm, thickness of 0.25 mm, length of 10 km) and Pipe B (diameter of 8 mm, thickness of 0.25 mm, length of 10 km). From experiments, the parallel ladder technique can eventually reduce the liquid residual inside the pipe. For Pipe A, the residual was reduced from 1.468 mg to 0.045 mg or 3.65 %. For Pipe B, the residual was reduced from 1.916 mg to 0.054 mg or 7.29%. The average oil residual purged out from Pipe A and Pipe B were 1.42 mg or 96.35%, and 1.86 mg or 92.71%, respectively. It can also be indicated that water and oil residual in the pipe were significantly less than the standard limitation (0.1 mg/m or 30%).

An experimental study of natural lighting for energy conservation using top-up control method

This paper presents the experiment-based analysis of interior illuminance from natural lighting through clear glazed window of a reference room located in Bangkok, Thailand, during February to May 2007 as a case study. The point illuminances measured by photoconductive sensors were collected every 5 minutes and the average interior illuminance from natural lighting were then calculated instantaneously. In this study, natural lighting also aims to reduce the requirement of electric lighting during daytime (7 am-5 pm) of the reference room. If natural lighting alone cannot supply the light at the required value, the electric lighting is assumed to be switched on under top-up control method to maintain the standard illuminance level. The average interior illuminance, which comprises of natural light and electric light, is controlled to be stable at the IES standard level of 500 lux. Nine sets of high performance lamp, 56 lm/W of efficacy, are assumed to supply the light to meet the standard condition. The requirements of supplementary lighting and possible savings during the test months are finally estimated.

Analysis of capacitive variation using parallel-plates method

Capacitive variation of capacitive sensor was analyzed by using two parallel plates coated by 0.4 mm- thick nylon and fixed together by resin to maintain the distance of those two plates at 2.5 mm and 5 mm. In this study, stainless and copper were used for development of capacitive sensor. In this paper Ethel alcohol solution is used as a case study. Ethel alcohol solution with the concentration ranging from 95% to 5% with 10% step decrease of concentration diluted by distilled water was experimented under the controlled temperature of 23 °C and the frequency was varied from 100 Hz to 2 kHz with 500 Hz interval. The capacitive variation analyzed from the equivalent circuit which was obtained from the developed sensor was then compared to the electrical circuit obtained from the Good Will R-L-C instrument model CRT to analyze for the appropriate material and the distance between two parallel plates (d) of the sensor. This proposed methodology was developed with consideration of the simple design for easy fabrication and low costs with high accuracy and reliability of the results.