A currently profitable sweet shop is producing $0\mathrm{.}4k\frac{g}{s}$ of waste hot water at $75$ deg $C$ from its

dishwashing operations. The shop is considering installing a counter current heat exchanger to recover

energy from the waste hot water to preheat the fresh water fed to the dishwasher which enters at $25$degC.

This will help in reducing its current energy requirements. However, a pump also has to be installed to

pump the waste water which is estimated to consume $0\mathrm{.}4kW.$ Assume a minimum approach temperature

of $10$degC is used in the heat exchanger and the overall heat transfer coefficient is $800\frac{W}{m^2}K.$ Specific

heat capacity of water is $4186\frac{J}{k}gK$

$($a$)$ Compute the installed cost of exchanger if the cost correlation for the exchanger is $Rs31500A^{0\mathrm{.}83},$

where $A$ is in $m^2.$

$(5$ points$)$

$($b$)$ Determine the installed cost of the pump if it requires $0\mathrm{.}4kW$ and the cost correlation is Rs

$400000P^{0\mathrm{.}36}$ where $P$ is the power in $kW.$

$(2$ points$)$

$($c$)$ Compute the net savings due to installation of exchanger if the hot utility cost is Rs $\frac{2}{k}Whr,$ the

electricity cost is Rs $\frac{8\mathrm{.}5}{k}Whr,$ annual maintenance and labour costs for the system is Rs $75,000,$

and the number of hours of operation is $1750hrs.$

$(3$ points$)$

$($d$)$ If the lifetime of the equipments is estimated to be $5$ years and the required rate of return on

investment is $20\%$ would you recommend installation of the heat recovery system, based on net

present value analysis?

$(5$ points$)$

$($e$)$ If the tax rate is $33\%$ and tax savings can be availed on the installed system using straight line

depreciation would you recommend installation of the system?

$(5$ points$)$