Suction Accumulator Sizing
By Kem Russell, PE
VP Engineering

Sizing of suction accumulators can be challenging due to the varying conditions that exist in a system. There are however a few principles that should be considered when determining the diameter and length of a suction accumulator.

First, what is the refrigerant that will be used? Due to the differences in refrigerant properties, in particular, vapor and liquid density, the design velocity through a vessel will change. As the temperature of the refrigerant decreases, the vapor density reduces and the vapor velocity through the vessel can usually be increased. For example, for ammonia at 20°F a design vapor velocity of 120 to 130 fpm is generally appropriate. If the temperature is -40°F, a vapor velocity of 220 to 240 fpm may be appropriate.

Second, will the pressure (and temperature) in the vessel vary over time? As mentioned above, as the vapor temperature changes the vapor density changes. For example, in a processing facility the refrigerant temperature may start out high (and likely will) then decrease as the system, and product load and flow rate balance out. Under these conditions the design velocity through the suction vessel may need to be lower than what the normal operating conditions would dictate. For example a -40°F system might better be designed for velocity in the range of 180 to 200 fpm to deal with the warmer vapor during startup.

Third, what is the vessel orientation? Will the vessel be horizontal or vertical? The positioning of the inlet and outlet connections of the vessel will also be important. For the vertical vessel usually the entire diameter of the vessel can be used as the separating area. However, for a horizontal vessel any liquid in the vessel will reduce the vapor area available for droplet separation. For horizontal vessels it is important to have the inlet and outlet connections far enough apart that the critical size droplets can fall to the liquid surface before they travel the horizontal distance between the connection points.

Fourth, what is the flow rate through the vessel? This can be determined from the CFM of the connected compressors, or the refrigeration capacity of the compressors. Ultimately, the CFM will be needed in determining the vapor area required for proper separation in the suction accumulator. For determining the vessel area required the equations used is usually Area = Compressor CFM/Design Vapor Velocity.

As you might guess, there are many factors that should be addressed when sizing a suction accumulator. There are some "rules of thumb", but following correct design principles tempered with experience will make the difference between success and trouble.

The President - Wayne Gohl

2002 turned out to be as much of a challenge as 2001 was for the construction industry. Here at Doubl-Kold we had to make some the same difficult decisions and sacrifices that many of our clients were also facing. We had to analyze every aspect of the business and make cuts, including the elimination of some in-house positions, to be able to operate efficiently in these lean times. 2003 fortunately is showing signs of being a better year for the industries that Doubl-Kold does the majority of its' business with. From the quoting activity we are already experiencing, we anticipate an upturn in business for 2003. We had several nice projects in 2002, including work for Zirkle Fruit, Valley Fruit, Kershaw Fruit, Peter Pan Seafoods, Mercer Ranches, and Royal Ridge to name a few. We also completed a large project for Sysco Food Services in Kent, WA and a large storage for Evans Fruit at their Mattawa Facility. Our Controls Dept. had several projects this past year including a large upgrade for both Inland-Joseph and Roy Farms. While 2002 may have been slow for new construction it was very busy for our Service Department, which did more overhauls for both screw and recip compressors than in any previous year. Our service techs responded to nearly a 1000 service calls in 2002. We continue to add new clientele such as Trident Seafoods, Columbia Beverage and Symons Frozen Foods to our long list of satisfied customers. We cherish these long time customers and their relationships and will continue to stride to deliver them a quality product and support long into the future.

Energy Incentive Programs

By John Cockrum, VP Controls Economic times continue to challenge the operation of refrigeration plants both large and small. Having an energy study done will usually produce several system efficiency upgrade suggestions. One of the best methods to achieve energy reductions has been the use of an accurate, precise control system tailored to the industrial refrigeration operation. Many utilities and local governments offer incentives, tax credits, or loans to offset the cost of energy efficiency projects. It is not unusual for 50% or more of the project cost to be covered. In addition, several utilities will cover some, or all of the cost to perform an energy study. It is important to inquire with your local utility to find out what programs are available for efficiency programs before a project begins. To learn more about how you can get a more reliable, productive, and energy-efficient facility with lower operating costs, give us a call!

Thank You to Our Valued Customers

By Ken Adams, VP Sales Let me take this opportunity to thank you for the business that you provided us this year. We are proud to welcome satisfied clientele and look forward to many years of working together. We look forward to your success in a struggling economy that is beginning to show some positive activity. We at Doubl-Kold are here to support you with the selection of energy efficient refrigeration systems that will provide you with the best return on your investment. We are committed to providing quality work with reliable equipment, and completing projects on time. Please contact us if we can assist you with any Refrigeration requirements that you may need.

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