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.
Energy conservation is a very interesting field. With the advances of technology we have items like solar panels for energy generation or water heating, battery technology for energy storage and new forms of lighting like LED lamps. A recent article on LED lamps caught my attention recently and I thought it would be a good example for comparison to ammonia refrigeration systems.
By now many of the States in the upper midwest have experienced very cold weather. As some have found, winter time presents some occasional challenges for starting or operating an ammonia refrigeration system.
I usually observe the surroundings and watch for the color change of the trees during this time of the year. As I was driving back from a project this last week I happened to notice something I thought was slightly ironic. At one bend in the highway there were patches of steam over the horizon. These are certainly more visible during this time of year with cooler ambient weather conditions. As I drove closer to the facility the source of the steam became apparent.
In the final entry on this series, the application of hand expansion valves (HEV) to liquid overfeed systems will be discussed. The application of HEV’s in this type of system somewhat differs from those of the prior discussions. When selecting HEV’s for the evaporators where liquid overfeed is being utilized the hand expansion valves take on a secondary function, which may not be obvious at first glance.
In this entry a unique application for hand expansion valves (HEV) is discussed. Many vessels in industrial refrigeration systems have what we call “float columns”. These float columns usually have mechanical float switches which actuate on predetermined liquid levels within the vessel. It is also common to find capacitance type level probes installed in the float columns to monitor liquid level in the attached vessel.
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.
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?
