I am really stuck, don't know what to do.Quote:

A heat exchanger produces steam by boiling water within vertical tubes, as shown in Figure 3.1

i)Water is supplied at a rate of 2 kg s–1 and an initial temperature of 80°C. Calculate the rate of heat transfer required to produce saturated steam at 140°C. What would the pressure in the top of the heat exchanger be (in kPa gauge)?

ii)The water/steam passes through a bundle of 50 vertical tubes, each of 3 cm internal diameter, 4 cm outer diameter, and 4 m in length, made of stainless steel with thermal conductivity 19 W m–1 K–1. Calculate the overall resistance to heat transfer across the tube walls. Hence calculate the required temperature driving force to deliver the heat transfer rate calculated in part (i).

Any help appreciated.