Gregory J. Zdaniuk

A survey of cooling tower water quality for condenser tube fouling potential

Abstract Fouling from cooling tower water is a serious problem in both power and refrigeration industries. The effect of fouling on enhanced tubes could be worse than that on smooth tubes because fouling may degrade the superior heat transfer performance by filling the gaps between the roughness elements with foulant. Condensers that use cooling tower water usually experience four different fouling mechanisms: corrosion, scaling, particulate, and biological fouling. Corrosion is prevented with chemical inhibitors, which pacify the piping and protect the metal surfaces. Cooling tower water can also be treated with biocide to prevent biological fouling. Therefore, the current paper addresses scaling and particulate fouling. The paper also establishes a database of water quality based on chemical analysis of samples collected from cooling towers across the country. The objective of the database is to determine water qualities that are typical of those found in actual cooling towers. From chemical analysis, three water qualities were determined: having an average fouling potential, a low fouling potential, and a severe fouling potential. These water qualities can be used in experimental determinations of fouling resistances in augmented tubes.

A literature survey of water-side fouling applicable to cooling tower condensers

Abstract Because of the complexity of fouling, it has been primarily studied as individual mechanisms. However, in actual field conditions, multiple mechanisms may be present. Little is understood about how different mechanisms interact. In cooling tower applications, water is treated with corrosion inhibitors and biocides to eliminate biological and corrosion fouling mechanisms. The fouling in cooling towers is, therefore, typically a combination of precipitation and particulate fouling. This paper presents a literature survey of research in the area of particulate, precipitation, and combined fouling modes in heat exchangers that use cooling tower water. Several experiments, models, and correlations are briefly described. The article concludes with a review section on long-term fouling data.

An Efficient Method to Find Solutions for Transcendental Equations with Several Roots

This paper presents a method for obtaining a solution for all the roots of a transcendental equation within a bounded region by finding a polynomial equation with the same roots as the transcendental equation. The proposed method is developed using Cauchy’s integral theorem for complex variables and transforms the problem of finding the roots of a transcendental equation into an equivalent problem of finding roots of a polynomial equation with exactly the same roots. The interesting result is that the coefficients of the polynomial form a vector which lies in the null space of a Hankel matrix made up of the Fourier series coefficients of the inverse of the original transcendental equation. Then the explicit solution can be readily obtained using the complex fast Fourier transform. To conclude, the authors present an example by solving for the first three eigenvalues of the 1D transient heat conduction problem.

Improving the Efficiency of the Advanced Injection Low Pilot Ignited Natural Gas Engine Using Organic Rankine Cycles

Intense energy security debates amidst the ever increasing demand for energy in the country have provided sufficient impetus to investigate alternative and sustainable energy sources to the current fossil fuel driven economy. This paper presents the Advanced injection Low Pilot Ignition Natural Gas (ALPING) engine as a viable, efficient and low emissions alternative to conventional diesel engines, and discusses further efficiency improvements to the base ALPING engine using Organic Rankine Cycles (ORC) as bottoming cycles. The ALPING engine uses very small diesel pilots, injected early in the compression stroke to compression-ignite a premixed natural gas–air mixture. It is believed that the advanced injection of the higher cetane diesel fuel leads to longer incylinder residence times for the diesel droplets, thereby resulting in distributed ignition at multiple spatial locations, followed by lean combustion of the higher octane natural gas fuel via localized flame propagation. The multiple ignition centers result in faster combustion rates and higher fuel conversion efficiencies. The lean combustion of natural gas leads to reduction in local temperatures and oxides of nitrogen (NOx) emissions, since NOx emissions scale with local temperatures. In addition, the lean combustion of natural gas is expected to produce very little particulate matter (PM) emissions (not measured). Representative baseline ALPING (60° BTDC pilot injection timing) (without the ORC) half load (1700 rev/min, 21 kW) operation efficiencies reported in this study are about 35 percent while the corresponding NOx emissions is about 0.02 g/kWh, which is much lower than EPA 2007 tier 4 heavy duty diesel engine statutes of 0.2 g/kWh. Furthermore, the possibility of improving fuel conversion efficiency at half load operation with Organic Rankine Cycles using “dry fluids” are discussed. Dry organic fluids, due to their lower critical points, make excellent choices for bottoming Rankine cycles. Moreover, previous studies indicate that “dry fluids” are more preferable compared to wet fluids because the need to superheat the fluid to extract work from the turbine is eliminated. It is estimated that ORC–turbocompounding results in fuel conversion efficiency improvements of the order of 10 percent while maintaining the essential low NOx characteristics of ALPING combustion.Copyright