| Abstract | A comparative study has been done to characterize the performance of various techniques
for upgrading industrial thermal effluents. Ten different techniques are evaluated using a computer
simulation model to predict their performance based on the commonly used performance criteria,
namely Coefficient of Perfo1mance (COP), Exergetic Efficiency (Nex), Primary Energy Ratio (PER),
and Unit Energetic Operating Cost (UOC). The variations of the two main parameters, waste heat
temperature (Twh) and temperature boost (Tb), as well as the other important optimising parameters
such as circulation ratio, concentration difference, value of low level heat (vb), temperature
difference of the heat source entering and leaving the evaporator (DTE), pinch point temperature,
and ratio of the mass flow rate of motive steam to the mass flow rate of suction vapor (ma/mb),
affect largely the perfo1mance of these techniques. The UOCs of the said heat pumping techniques
are evaluated for five developing countries in Asia, namely Thailand, Indonesia, Malaysia, Pakistan,
and the Philippines. The performance of these heat pumping devices is influenced by different price
structures of electricity and various fuels in every country.
The potential application of upgrading thermal effluents has been studied in two industries
in Thailand. Considerable energy saving and fuel cost saving can be obtained through the possible
integration of heat upgrading devices into the industrial process. The temperature at which the
degraded quantity of waste heat is rejected affects these energy and fuel cost savings. The system
which gives the highest savings is Organic Rankine Cycle (ORC). No fuel cost is incurred using
ORC since it does not use high level energy in the system. In the economic evaluation, heat
transformer always gives the lowest monetary savings in all cases. However, whenever waste streams
are available, the application of heat transformers cannot be dismissed as insignificant since heat
transformers upgrade waste streams without the use of high grade energy. Economic evaluation
done in this study does not include capital or investment cost and pay- back period. The
pe1fonnance of heat upgrading devices may be altered by these factors. |