000 04313ntm a2200373 i 4500
001 vtls000103165
003 KUKTEM
005 20251117113358.0
008 180326t20182018my da f am 000 0 eng d
020 _aTHE0005277(Local)
039 9 _a201905141732
_bhanafiah
_c201903211648
_dsaini
_y201803261227
_zsaini
040 _aUMP
_beng
_cUMP
_erda
090 _aFKM .T45 2018 r Thesis
100 0 _aThiwaan Rao Narasimma Naidu,
_eauthor.
245 1 0 _aFlow and heat transfer characteristics of supercritical carbon dioxide in mini-channels /
_cThiwaan Rao A/L Narasimma Naidu
264 1 _aKuantan, Pahang :
_bUMP,
_c2018
264 4 _c© 2018
300 _axvii, 117 pages :
_billustrations (some color), charts ;
_c30 cm. +
_e1 CD-ROM
336 _atext
_2rdacontent
336 _atext
_2rdacontent
337 _aunmediated
_2rdamedia
337 _acomputer
_2rdamedia
338 _avolume
_2rdacarrier
338 _acomputer disc
_2rdacarrier
347 _atext file
_bPDF
_2rda
500 _aFaculty of Mechanical Engineering
502 _aThesis (Master of Science in Mechanical Engineering) -- Universiti Malaysia Pahang – 2017
504 _aIncludes bibliographical references
520 3 _aSupercritical carbon dioxide (scCO2) is being used in many engineering applications because at supercritical stage, it has unique thermal properties with enhanced heat transfer and flow characteristics. Carbon dioxide (CO2) at supercritical phase is being used recently in Heating, Ventilation, Air Conditioning, and Refrigeration (HVAC&R) industries due to its special thermal properties of supercritical CO2. However, the effects of some process and geometrical parameters on the thermal hydraulic performance of scCO2 are not fully examined. Thus, the aim of this study is to develop single phase flow and heat transfer model and to investigate the effect of some process parameters (inlet pressure, inlet temperature, and inlet flow rate) and geometrical parameters (Tube inner diameter and tube shape) on the performance of scCO2 cooling process. For the numerical investigation, two cases were considered: straight and helical tubes at various tube diameters. The model was developed based on the assumption that the scCO2 flow is incompressible, turbulent and non-isothermal. The developed numerical model was validated using experimental data from open literature for the straight tube and by conducting experiments for the helical tube case. Both the simulation and experiment were performed at various input parameter range: pressure (7.0 MPa – 10 MPa), temperature (35 ºC – 80 ºC), flow rate (10 L/min – 35 L/min) and tube diameter (2.8 mm – 4.5 mm). The model validation results indicated that the average percentage error between the simulation and experimental results were less than 10%. This indicates that the developed model can be used to predict the performance of scCO2 cooling process. Both the experimental and simulation results indicated that the heat transfer coefficient reaches peak value near the pseudo-critical point. Heat transfer coefficient decreased as inlet pressure increased beyond critical point but increased with increasing flow rate. Meanwhile, highest pressure drop value was recorded near the critical point. On the other hand, the smaller the inner tube diameter the higher the heat transfer coefficient will be. The pressure drop in a system decreased when the system inlet pressure is increased but increased with increasing flow rate. Besides, the sensitivity analysis results of Nusselt number and pressure drop indicate that the best input parameters in scCO2 cooling. Inlet pressure with value near critical point, smaller tube ID and higher flow rate could achieve both enhanced heat transfer and low pressure drop at the same time. However, increasing inlet temperature could deteriorate heat transfer rate even though lower pressure drop was attained. These parameter combinations could help reducing the pumping power associated with pressure drop.
610 2 0 _aFaculty of Mechanical Engineering
_xDissertations
650 0 _aUniversities and colleges
_xDisertations
650 0 _aTheses
999 _aVIRTUA40
_c7647
_d7653
999 _aVTLSSORT0080*0200*0400*0900*1000*2450*2640*2641*3000*3360*3361*3370*3371*3380*3381*3470*5000*5020*5040*5200*6100*6500*6501*9992