*4.2. Economic Evaluation*

Figure 8 presents the daily DO volume consumption of boiler for 7 months. Depending on the demand, the DO fuel consumption changes daily, higher DO fuel consumption corresponding to higher demand and vice-versa. From the collected data as presented in Figure 8, the average volume of DO consumption is evaluated about 600 L/day, among which about 30% was used in the production of steam for laundry, equivalent to 200 L/day. Thus, the average volume of DO consumption corresponding to the supplied hot water is 400 L/day. Based on this data, the annual savings (*E*) for reducing the volume of DO fuel consumption was evaluated in the Table 8. The hot water supply system using EGH of ICE could eliminate the existing boiler system which results into fuel savings utilized to run the existing system. The annual saving of 110,880 \$/year could be achieved using the proposed system. The total cost of new system (*C*) at the current time was estimated as shown in Table 9. The payback time (*T*) was defined: *4.2. Economic Evaluation* Figure 8 presents the daily DO volume consumption of boiler for 7 months. Depending on the demand, the DO fuel consumption changes daily, higher DO fuel consumption corresponding to higher demand and vice-versa. From the collected data as presented in Figure 8, the average volume of DO consumption is evaluated about 600 L/day, among which about 30% was used in the production of steam for laundry, equivalent to 200 L/day. Thus, the average volume of DO consumption corresponding to the supplied hot water is 400 L/day. Based on this data, the annual savings (*E*) for reducing the volume of DO fuel consumption was evaluated in the Table 8. The hot water supply system using EGH of ICE could eliminate the existing boiler system which results into fuel savings utilized to run the existing system. The annual saving of 110,880 \$/year could be achieved using the proposed system. The total cost of new system (*C*) at the current time was esti-

$$T = \frac{\ln\frac{E}{E - i\*c}}{\ln(1+i)} \ast 12 \text{ months} \tag{21}$$

where *i* is the compound rate yearly, taken *i* = 20%/year. Thus, the payback time is evaluated as *T* = 09 months from Equation (21). where i is the compound rate yearly, taken i = 20%/year. Thus, the payback time is evaluated as *T* = 09 months from Equation (21).

mated as shown in Table 9. The payback time (*T*) was defined:

**Figure 8. Figure 8.**Daily DO volume consumption of boiler. Daily DO volume consumption of boiler.


**Table 8.** Annual savings of recovered EGH.

**Table 9.** Cost of the new hot water system.

