Disclosed is a process of performing Sexual PCR which includes generating random polynucleotides by interrupting or blocking a synthesis or amplification process to show or halt synthesis or amplification of at least one polynucleotide, optionally amplifying the polynucleotides, and reannealing the polynucleotides to produce random mutant polynucleotides. The sub-cooling unit receives a portion of the coolant diverted from the line to cool coolant flowing in the line. The baffles are interconnected along the length by cross connectors to ensure rigidity. In addition, exhaust steam from the steam turbine is also used to cool the gas turbine.