excess heat is rejected to the environment. Any electricity shortage is made up with imports. Process steam shortages are made-up by an auxiliary boiler.
2) Prime movers are specified to always meet the entire electrical load of the user. Steam or heat demand is met by the prime mover. An auxiliary boiler is fired to meet any excess heat deficit and excess heat is rejected to the environment.
3) Prime movers are operated to just meet the steam or heat load. In this mode, power deficits are made up by purchased electricity. Similarly, any excess power is sold back to the utility.
For load analysis, Lee considers that “demand of the user is continuously changing. This requires that data on the electrical and thermal demands of the user be available for at least one year.” He further states that
“electrical and heat demands of a user vary during the year because of the changing working and weather conditions.” However, for evaluation purposes, he assumes that the working conditions of the user-production related CHP load-remain constant and “that the energydemand pattern does not change significantly from year to year.” Thus, to consider working condition variations, Lee classifies the days of the year as working and nonworking days. Then, he uses “average” monthly load profiles and “typical” 24-hour load profiles for each class. “Average” load profiles are based on electric and steam consumption for an average weather condition at the site. A load profile is developed for each month, thus monthly weather and consumption data is required. A best fit of consumption (Btu/month or kWh/month) versus heating and cooling degree days is thus obtained. Then, actual hourly load profiles for working and nonworking days for each month of the year are developed. The “best representative” profile is then chosen for th