Maintaining System Efficiency

The flow of steam to a reboiler can be controlled by using a control valve on either (1) the steam inlet line or (2) the condensate outlet line. 

Now the rate or heat duty of steam condensation is termed Q  

Varying channel head pressure controls heat input. 

U = heat-transfer coefficient—a constant, describing the rate of condensation of steam, on those tubes exposed to the condensing steam (Btu/[(h)/(ft )(°F)]) 

AT = temperature difference between the shell and tube sides, °F Q = heat-exchanger duty, Btu/h (for the preceding equation in case 1 10,000,000 Btu/h) 

---

Maintaining System Efficiency Steam flow control... 

Valve types with low K values or L/D ratios are required due to the need to minimize pressure drop losses to optimize and maintain system efficiency. Hence, standard globe-type valves, angle or in-line... 

As anodes age their performance gradually deteriorates, and thus small changes in electrolyte composition must be made to maintain current efficiency and energy consumption. The EMOS system has been used by some operators to determine the optimum composition of the electrolyte in these circumstances and in some cases to control the composition selectively for each cell line. 

Cabrera and co-workers [28] reported the first combinations of monolithic columns (50 mm x 4.6 mm and 100 mm x 4.6 mm) and mass spectrometry detection, a novel system configuration able to demonstrate a doubling of throughput by using increased flow rates while also maintaining separation efficiency. 

Where experience with water chemistry, system metallurgy, or system operation suggests that only minimal waterside problems may occur, or where customer demands are for minimal expenditure, inhibitor treatments may consist of only simple formulations, such as a phosphonate/polyacrylate blend. Many cooling systems around the world, both large and small, do in fact operate on little more than just this type of simple low-cost approach. However, for the most part, the operators face an uphill battle to maintain operational efficiency, and many are unaware of the benefits to be gained by using a more comprehensive treatment program. 

Additionally, highly efficient heat exchangers are required in fuel processors and the micro si rue lured plate heat exchanger design seems to be the best solution so far to maintain the crucial system efficiency competitive. 

There is no hard requirement for constant speed operation of the compressor in the primary system. If one chooses to run at constant speed, then inventory control is used to maintain high efficiency. If variable speed is used, then inventory is maintained constant to remain near the peak efficiency point of the compressor. 

When constructing biosensors, which are to be used continuously in vivo or in situ, maintaining sensor efficiency while increasing sensor lifetime are major issues to be addressed. Researchers have attempted various methods to prevent enzyme inactivation and maintain a high density of redox mediators at the sensor surface. Use of hydrogels, sol-gel systems, PEI and carbon paste matrices to stabilize enzymes and redox polymers was mentioned in previous sections. Another alternative is to use conductive polymers such as polypyrrole [123-127], polythiophene [78,79] or polyaniline [128] to immobilize enzymes and mediators through either covalent bonding or entrapment in the polymer matrix. Application to various enzyme biosensors has been tested. 

---