| Summary: | 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, CFC-11 has been replaced by HCFC-123 as a transitionary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.
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