2016 ASHRAE Winter Conference

A major concern in the operation of cooling tower systems is the prevention of scale on heat transfer and evaporative surfaces. The process by which scale forms is not often clear or well explained, and the means by which scaling may be controlled is commonly not explained to any significant degree. This paper attempts to outline the mechanisms of scale formation, discuss chemically based and non-chemically based strategies for scale control, provide real-time instrumental data illustrating the effectiveness of both chemical and non-chemical control and then discuss the basic requirements for successful implementation of each strategy given the many chemical, physical and operational variables generally associated with cooling tower operation. Each strategy has its advantages and diadvantages and no one strategy is well suited under all circumstances. It is hoped that this paper will help clear up some of the misconceptions concerning chemical and non-chemical cooling water treatment and promote more meaningful and informed discussion during the treatment strategy selection process.

HVAC water systems (cooling tower/condenser water) are frequently operated without filtration—leading to reduced efficiency. Filtration selection for cooling tower water is accomplished by determining the type of solids present in the water, water quality requirements, physical space availability, weighing the pros and cons of the various filtration options and budget constraints. Selecting the wrong type of filtration is akin to taking vitamins for pain relief: good product but wrong application. This paper compares the differences between barrier and non-barrier filtration options and when to apply each option. Either type of filtration, when correctly applied, assists HVAC equipment to operate at design efficiency.

Awareness of non-chemical processes and the successes of various technological solutions to common water treatment problems are now well established. Despite detractors, non-chemical and physical water treatment products continue to make their mark by providing results that meet and exceed water treatment industry standards. Although initially propelled by the greening of the built environment, physical water treatment now stands as a viable alternative to traditional chemical programs. The debate over whether these technologies work is over, with the new discussions centered around when and how to apply them. With technological progress and continued innovation, these once-experimental technologies have given birth to experienced and proven methodologies. This paper covers the history of various technologies and examines the plusses and minuses of each class of non-chemical water treatment. It illustrates how the latest advancement improves on pulsed power and in combination with advanced suspended solids management provides unmatched savings of water and energy, while matching or exceeding the performance metrics of modern water treatment deliverables.

The debate continues between the use of non-chemical water treatment devices and chemical water treatment for treating cooling water systems. The goals of any cooling water treatment program are to protect against corrosion, deposition and microbiological fouling. This paper presents the chemical water treatment method to accomplish the best performance standards. In doing so, the authors critique both and highlight the benefits of chemical water treatment. The authors present results of trials where both technologies have been used to treat cooling water and discuss the methodologies behind each technology. Many providers promote “green,” “safe” and “economical” as the reason to use a certain technology. Many users select their appropriate method of treatment based on these same factors. What factors should determine the type of treatment? When we define success, we can determine the best method to achieve it.