About the authorMike Fisher has over 35 years of experience with refrigeration systems. This background includes; service, installation, equipment manufacturing, research and development, project management, consulting engineering, system design and packaged systems.
In the previous blog entry we discussed the use of hand expansion valves (HEV) maintaining a liquid level in a vessel. In this entry the discussion will center on the HEV being utilized as an expansion device to an evaporator being fed with liquid from a controlled-pressure receiver (CPR).
We have been somewhat busy the last few weeks completing a new project. The next few blog entries should be more timely.
These valves are used for multiple purposes in ammonia refrigeration systems. However, they are commonly designated by a single description. This common term of hand expansion valve (HEV) is sometimes misleading. It may help to consider the actual function the valve provides; throttling of liquid or vapor and the mass flow requirements for the application.
The common applications of this valve are:
The next few blog entries will discuss the multiple applications of these valves.
We have worked on several projects with a local contractor where stainless steel was used for the ammonia piping system. One of the most obvious benefits of using stainless steel over carbon steel is the elimination of corrosion. The use of carbon steel piping presents a challenge to work with, even though it has been the most common piping material in use for ammonia refrigeration systems.
If you think you may have a problem with draining liquid ammonia from your evaporative condensers, you may want to investigate the equalizing line. This piece of pipe is typically installed on top of the high pressure receiver. The termination of this pipe is usually the discharge line leading to the condensers.
What follows is a brief description of how the equalizing line works.
Much of the material used for ammonia refrigeration systems is carbon steel. Though various grades of this material are used for pressure vessel fabrication or piping there is one common problem associated with this.
When your ammonia refrigeration system exhibits a recurring problem issue, how do you solve it? Do you look for the the underlying factors that cause the component to react in the manner it did, or do you replace the component because it did not operate as intended?
For those who own and operate large ammonia refrigeration systems the consequences of this legislation may be far reaching.
Disregarding any political or environmental viewpoints on this subject one issue that should be interesting to discover is the impact of this legislation on associated energy costs, if the bill passes.
One issue that may come up during an audit is replacement of ammonia. If you have added ammonia to your refrigeration system someone may ask you:
This may put you in an untenable situation with trying to find an explanation for seemingly ordinary maintenance practices. Where might you find a potential, unnoticed source of ammonia loss?
Owners and managers of cold storage warehouses are often faced with minimizing their operating costs. The energy used by the refrigeration system is often a major contibutor to this cost of operation. In the attempt to limit the energy used and its subsequent cost various methods can be utilized.
What impact does location have on your energy use? Obviously, if you are located in the South or Western part of the US your ambient temperatures (wet bulb or dry bulb, depending on condenser type) will be higher year round. This can limit your efforts to lower the discharge pressure.
