An electric inner-city bus with 500km range and consumption rate of 300 Wh/km is equipped with a lithium-ion battery pack and a bank of supercapacitor to capture the regenerative breaking energy and assist in acceleration and hill climbing, with the following specifications: Battery pack: Voltage 400V, and Energy = 150kWh,
Supercapacitor bank: 150V, and energy = 450Wh

a. Design the battery pack from building block cells that has 4V and 10 Ah capacity.
b. Design the supercapacitor bank from capacitor cells with 3V and 3600F capacitance.

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 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?