Heat Exchanger Cost
1. The problem asks to find the 2000 purchased cost of similar shell-and-tube heat exchangers with different heating surfaces, starting from a 1990 cost of $4200 for 100 m^2.
2. The chemical engineering plant cost index is applied to update the cost from 1990 to 2000.
3. The capacity cost estimation formula is:
$$C_2 = C_1 \times \left(\frac{A_2}{A_1}\right)^n \times \frac{I_2}{I_1}$$
where:
- $C_1 = 4200$ is cost in 1990 for 100 m^2
- $A_1 = 100$ m^2
- $A_2$ is new heating surface area (given for parts c and d)
- $n$ is the capacity exponent
- $I_1$ is cost index for 1990
- $I_2$ is cost index for 2000
4. From Chemical Engineering Plant Cost Index, the approximate values:
- $I_{1990} = 370.2$
- $I_{2000} = 459.2$
### Part c: 30 m^2 heating surface, $n=0.6$ (surface range 10-40 m^2)
$$C_2 = 4200 \times \left(\frac{30}{100}\right)^{0.6} \times \frac{459.2}{370.2}$$
Calculate:
1. $\left(\frac{30}{100}\right)^{0.6} = (0.3)^{0.6} \approx 0.4857$
2. Cost index ratio: $\frac{459.2}{370.2} \approx 1.2406$
3. So,
$$C_2 = 4200 \times 0.4857 \times 1.2406 \approx 4200 \times 0.6026 = 2530.9$$
### Part d: 175 m^2 heating surface, $n=0.81$ (surface range 40-200 m^2)
$$C_2 = 4200 \times \left(\frac{175}{100}\right)^{0.81} \times \frac{459.2}{370.2}$$
Calculate:
1. $\left(\frac{175}{100}\right)^{0.81} = (1.75)^{0.81} \approx 1.6158$
2. Cost index ratio: $1.2406$ (same as above)
3. So,
$$C_2 = 4200 \times 1.6158 \times 1.2406 \approx 4200 \times 2.004 \approx 8416.8$$
### Part 2: Total capital investment in 2000
The problem states โtotal capital investment needed from problem 1 in 2000โ. Assuming this means summing costs for both sizes:
$$Total = 2530.9 + 8416.8 = 10947.7$$
**Final answers:**
1. c) New cost for 30 m^2 heating surface in 2000 is approximately $2531$
2. d) New cost for 175 m^2 heating surface in 2000 is approximately $8417$
3. Total capital investment needed for both in 2000 is approximately $10948$