Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Mechanical Engineering

First Advisor

Gerald M. Colver


Many of the techniques have been proposed to improve the dryer efficiency. The drying process has not been analyzed thoroughly. The experimental results of 32 runs of a Frigidaire clothes dryer are presented. The dryer is fully instrumented to measure the instantaneous air temperatures, the instantaneous surface temperatures, the instantaneous power, and inlet, and outlet flow rates. The effect of many of the dryer parameters such as heater power, fan speed, drum speed, weight of clothes and initial moisture content were experimented, documented, and analyzed. The results were discussed and many new proposed techniques to improve the dryer performance were recommended.;Electric heaters are used in many industrial applications. There are many interacting parameters that affect the heater performance and contribute to its cost. Such parameters are coil length, coil diameter, the helix diameter, the number of turns, the coil emissivity, the heater wall emissivity, the applied voltage, the air flow rate, the air temperature at the heater outlet, and the heater dimensions. The heater coil was divided into four segments and the heater wall was divided into five sections. Energy and heat transfer equations were written for each segment of the coil, each section of the wall, and the air past each coil segment. Equations relating the configuration factors from the coil segments to the wall sections, to the heater dimensions were derived. EES was used to solve the system of two hundred non-linear equations. The effect of varying the heater parameters on the heater performance were studied and discussed. The objective function is constructed for the annual cost of an appliance electric heater using an estimate for the energy usage and the manufacturing cost. A detailed model for the electric heater is utilized to minimize the objective function relative to nine design variables, subject to thirteen inequality constraints. Experimental results are used to correlate the mass flux to the dryer input parameters. The correlation is used to determine the running cost. The objective function of the annual running cost plus the cost of the heater is optimized using different methods. The optimization results are presented and discussed.



Digital Repository @ Iowa State University,

Copyright Owner

Ashraf Maurice Bassily



Proquest ID


File Format


File Size

335 pages