Question

You have been asked to design a similar pump from the existing one. The existing pump works for water is of impeller diameter equals 6 cm and its performance data is shown here when working at 1725 rpm. The newly design pump is for a refrigerant (R-134A) and it must produce 450 cm of head at 1600 rpm when working at its best efficiency. One of your colleagues did preliminary analysis and develop the performance curves in dimensionless form for the existing pump family which is also shown below

Question No. 2: (15 You have been asked to design a similar pump from the existing one. The existing pump works for water is of impeller diameter equals 6 cm and its performance cm/s data is shown here when working at 1725 rpm. The newly design pump is for a refrigerant R-134A) and it must produce 450 cm of head at 1600 rpm when 100 200 working at its best efficiency. One of your colleagues did preliminary analysis and 300 develop the performance curves in dimensionless form for the existing pump 400 family which is also shown below 500 1.6 600 700 Hem 180 185 175 170 150 95 54 32 54 70 79 81 66 38 CX 10 1.2 BEP Your task is to determine the following for new pump a) Diameter of the impeller, bi The volume flow rate at best efficiency. Power requirement at the best efficiency, d Shutoff head Free delivery 1.8 1.6 1.4 "pump 0.2 CX 100 0 0 0.5 1.5 2 Cox 100

Answer 1

DATE = 6 cm For existing pump: (pump) D RPM, N,= 1725 rpm density of water , Sw= 1000 kg/m3. For new pump: (pump 2) H₂ = 450 cm at best efficiency. N2 = 1600 rpm For pump 1 at best efficiency of 81% Hy = 150 cm Applying pump simi nilarity N,2 0,² N₂² D22 D22 = N, 2 D, 2 N₂2 x (1725)2x6602 (1600) 2 D2 a law, Н. H2 so H2 X. Hi 450 150 2 125.53

DATE D2 = 11.20 cm Aus b 3 At best efficiency point, from the given curve, volumetric officiency flow rate = 1.1x100cm 110 cm3 S on s ro Powere requirement at best efficiency 0.19 X 100 kW 19 KW D Shutoff head = Head at minimum flow. 1.45 X 10 cm 14.5 em 1 11

DATE @ Free Free delivery - flow that 7.7 7. can makinium occur 1.8 X 100 - cm3 s 180 cm² s sus

1.6 shut off head CX 10 BEP → Best efficiency point. 0.8 0.6 Free delivery head 0.9 0.2 Powere at eest efficiany Cpx 100 Free delivery flow Co X 100 volumetric How rate at best efficieny point