The Numerical Simulation of Diluting Toxic Gas with Forced Ventilation

• Main Authors: Dihng-Yueh Tzeng, 曾定嶽
• Other Authors: Jenq-Shing Chiou
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/55507835604348839088

碩士 === 國立成功大學 === 機械工程研究所 === 84 === The harmful ultraviolet rays will directly irradiate the earth due to the damage of ozonosphere caused by the use of CFCs , the major manufacturers of refrigerants have already stopped the production of CFCs in this January (1996) . Compare to CFCs , HCFCs have much less lethality to ozonosphere , so it becomes a transitionary replacer in the use of refrigerants . Nowadays , CFC-11 has been replaced by HCFC-123 as a transitionary refrigerant in centrifugal air handling unit . The toxicity of HCFC-123 may endanger operator''s health due to refrigerant leak while manipulating the air handling unit , therefore , it is an important task to keep the concentration of HCFC-123 below its safety level (10 ppm) . Since the use of fresh air to dilute the indoor air with refrigerant leakage is an effective way to lower down the refrigerant level . The design of ventilation system thus plays an important role in safeguarding operator''s health and safety . Recently , CFD has become a powerful tool in the analysis of fluid dynamics and heat transfer , and there have been many researchers who utilize CFD to simulate the problem of indoor air flow and pollutant diffusion . The applications of CFD indeed do a lot of help to the design of HVAC . This thesis uses CFD as a tool to analyze the leaking problem of R-123 and simulate the ventilating condition of mechanical equipment room . The purge performance via different ventilation systems and the relative diffusion of R-123 are discussed in this thesis . The UNIC code written by ESI is adopted in relevant numerical simulation in this thesis . To verify the reliability of this software , the experimental data obtained by D. B. Jouini is used to verify the accuracy of this computer code.