Mechanical Engineering ETDs

Publication Date



Electric utilities are today faced with the dilemma of satisfying increasing demands for electrical energy while their ability to build new power plants is being severely curtailed primarily due to environmental concerns. By redistributing the power demand of individual customers (and thus the utility) with respect to time, greater overall electricity consumption can be met without increasing the generating capacity of the utility. This redistribution can be accomplished using thermal energy storage at the customer’s location. For heating and cooling of buildings, thermal storage, combined with off-peak period operation of the mechanical system's major electricity consuming equipment, can lower peak period electric demand. Where energy-plus-demand or time-of-day rate structures are used, the savings in electricity costs can be substantial. In this thesis, a solar-augmented heat pump system with electric boiler backup and evaporative cooling (wet cooling tower) was analyzed. The boiler, evaporative cooler and heat pump were each constrained to operate during off-peak periods only, storing heating capacity or cooling capacity for use during the following peak period. It was found that while significant reductions in the peak electric demand quantity were possible, overall energy consumption generally increased. However, the net result was a decrease in the cost of electricity under an energy-plus-demand rate structure, as the penalty paid for increased consumption was not as great as the savings realized from the lower power demand. Most commercial and industrial firms operate under an energy-plus-demand rate structure and the applicability of off-peak heating and cooling system equipment operation could be widespread. If enough of these customers could implement such a plan, the utility’s peak demand would be expected to decrease, with the result that there would be less pressure for new plant construction. Without the cost of new construction, electricity rates might be expected to increase at a slower rate than would have been necessary previously.

Degree Name

Mechanical Engineering

Level of Degree


Department Name

Mechanical Engineering

First Committee Member (Chair)

Maurice Wilbert Wildin

Second Committee Member

Charles Gilbert Richards

Third Committee Member

Karl Thomas Feldman Jr.

Document Type