kern-0pt} {Q_{0} }}}} (24 where Qnr and Qnw are respectively the new recycled flow rate and the new waste flow rate.
In the case study, three periods (low, medium and high demand period) of demand for biodiesel are considered, whereby each period is subjected to uncertainties, i.e. waste oil flow rate, waste oil price and enzyme price.
Only effluent VFA and the sludge blanket height (SBH) have to be set as design criteria, and the optimisation algorithm obtains the minimum return sludge and waste sludge flow rates which fulfil those design criteria.
As the waste water mass flow rate varied from 0.83 m3/h to 1.87 m3/h, the effectiveness and exergy efficiency varied from 0.19 to 0.09 and from 34%to41%1%, respectively.
The results indicated that the exergy efficiency increased with the increment of waste water mass flow rate at constant fresh water mass flow rate, while the effectiveness decreased at the same operation condition.
As the waste water mass flow rate varies between 0.8 and 1.9 m3/h, exergy destruction rate, exergy efficiency and effectiveness of the HPHE have the values from 0.277 to 0.510 kW; from 66.1% to 42.9% and from 0.085 to 0.192, respectively.
While the waste water mass flow rate varies between 8 and 12 m3/h, exergy destruction rate, exergy efficiency and effectiveness of the PHE have the values from 5.55 to 13.68 kW; from 53.6% to 67.2% and from 0.996 to 0.810, respectively.
The experiments of pyrolysis were designed by response surface modeling of process parameters, including particle size of waste tire slices, flow rate of argon gas, amount of catalyst, and time and temperature of pyrolysis, related to the corresponding yields of oil, gas, and char.
The industrial waste heat parameters, like flow rate and temperature, usually fluctuate in a certain range due to the variation of upstream industrial process.
Optimum waste water and cold water mass flow rate was found as 10.00 and 7.00 m3/h, respectively.
