Interfacing a GPM device's thermal conductivity detector to a 80286 personal computer

Date

10-1996

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Demetrio A Yco, Jr.

Abstract

Interfacing the GPM Device's Thermal Conductivity Detector to a 80286 Personal Computer. Adviser: Prof. D.A. Yco, Jr. interfacing the Gas Purging and Monitoring(GPM) Device's Thermal Conductivity Detector(TCD) to a 80286 personal computer reduces the limitations of the instrument. With interfacing, we can automate data gathering and analysis, thus maximizing the number of data values read per unit time and minimizing manual monitoring and intervention. This makes the instrument more precise and cost-effective. Interfacing the GPM Device's Thermal Conductivity Detector to a microcomputer comprises three stages: developing the circuit of the Thermal Conductivity Detector(TCD) by using thermistors instead of the original nichrome wires as sensors so as to obtain a more stable voltage output signal; utilizing an Analog-to-Digital Converter card that would convert the analog voltage signal to a digital one; and making an interface program using Turbo Pascal V7.0, that would read, save to a datafile and graph the voltage signal generated by the TCD. Twenty data files were gathered for the study. They were of the following four different chamber temperatures 350°C,400°C,450°C and room temperature of 23°C with gas flowing at mass flowrates of 13-17 113/hr (CFH). The variation of the temperature of the gas flowing in the two paths of the GPM Device produced a signal in the TCD that was read every second by the interface device for a time duration of three minutes and was later saved to a data file. Temperature control of the chamber was accomplished by placing an insulated heating element made of Kanthalux wire beneath the gas chamber connected to wire beneath the gas chamber connected to a 1000 Watt, 110Volt Variac. The three high chamber temperatures were predetermined before data gathering. The characteristic function obtained in the study for high chamber temperatures of 350°C,400°C,450°C respectively and for a time duration of three minutes is:

Y = B x log(X) + A

where Y is the TCD voltage output value X is the time B is a constant and A is constant in voltage. The characteristic function obtained in the study for room temperature (23°C) and for a time duration of three minutes is:

y = ax2 + bx + c

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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