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The correction factor in Eqs. (6.21) and (6.23), takes into account the variations in the Prandtl number from the tube wall temperature Tw to the bulk temperature Tb. The wall temperature is defined as: ⎛&⎞ Tw =Tb −⎜ Q ⎟ ⎝h⋅A⎠ (6.27) When the convective heat transfer coefficient h increases, the wall tempe- rature will approach the bulk temperature of the fluid, and the correction factor will approach 1. Calculations showed that the variations in the correction factor for the CO2 flow typically would range from about 0.5 to 5% at 8 to 10 MPa gas cooler pressure and temperatures between 5 to 110°C. Regarding the water flow, the estimated variations ranged from about 0.5 to 2% at temperatures from 5 to 90oC. The variations in the correction factor were regarded as small enough to be neglected in Eqs. (6.21) and (6.23). 6.1.3.4 Pressure Drop Correlations The pressure drop for the single-phase supercritical CO2 as well as the water in each sub-section of the tripartite gas cooler was calculated from the following general equation (Incropera and DeWitt, 2001): ∆p=ζ⋅⎛⎜ L ⎞⎟⋅⎛⎜ρ⋅v2 ⎞⎟ (6.28) ⎜⎝dh⎟⎠⎜⎝ 2 ⎟⎠ where ζ is the friction factor, L the length of the sub-section, and ρ and v the density and mean velocity of the fluid, respectively. The following correlations from Gnielinski were used to calculate the friction factor for laminar and turbulent flow, respectively (VDI, 1993): 6 – Modelling ζ = ⋅ 1+ 0.033 ⋅ ⎢log ⎜Re⋅ ⎟⎥ (6.29) (6.30) 64 ⎡⎢ ⎡ ⎛ dh ⎞⎤4.0⎤⎥ LRe⎢ ⎢10⎜D⎟⎥⎥ ⎢ ⎣⎝ ⎠⎦⎥ ⎣⎦ 0.3164 ⎡ dh 0.25⎤ ζT = Re0.25 ⋅⎢1+0.095⋅ D ⋅Re ⎥ ⎢⎥ ⎣⎦ 179PDF Image | Residential CO2 Heat Pump System for Combined
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CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
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