7-70 Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4m-long tubes inside which the refrigerant is evaporating at 20C. Air approaches the tube bank in the normal direction at 0C and 1atm with a mean velocity of 4m/s. The tubes are arranged in-line with longitudinal and transverse pitches of SL=ST=1.5cm. There are 30 rows in the flow direction with 15 tubes in each row. Determine (a) the refrigeration capacity of this system and (b) and pressure drop across the tube bank. FIGURE P7-70