When adding or replacing equipment at a facility, it’s always best to build in time to explore your options. Once the decision is made that new equipment is necessary, it’s hard to avoid the pressure to enhance production now. Everyone wants -- and needs -- their equipment “yesterday.” But rush the decision and you may rue the day you signed the contract.
This month’s articles cover different equipment and components, but all urge you to a greater understanding of what exactly it will take to bring your company the production results required. Take enclosure cooling as an example.
The design and operation of a fan system in electronic enclosures present challenges you may not have expected. Jud Alexander, the engineering manager at Continental Fan Manufacturing Inc., Buffalo, N.Y., presents a good case for spending the time to evaluate your space and pressure requirements. In “Fan Design for Electronic-Cabinet Cooling,” Alexander notes that often the user’s cabinet choice revolves around an axial (propeller) or centrifugal fan, but that may not be the best tactic. While generating the airflow necessary to ventilate the cabinet is the goal, key factors to selecting the fan type are space considerations and pressure requirements.
A similar procedure exists for most any equipment -- even ammonia evaporators. According to “5 Advantages of Aluminum Evaporators,” by Bruce I. Nelson, P.E., president of Colmac Coil Manufacturing Inc., Colville, Wash., designers and installers of such systems need to examine the equipment’s weight, performance, corrosion-resistance, cleanability and defrosting characteristics. Such exploration may take them in an unexpected direction. Although air-cooling evaporators used in ammonia refrigeration systems traditionally have been made of galvanized (zinc-coated) carbon steel, other metals are compatible with ammonia, including aluminum.
Bryan Smith, internal operations manager at Cryoquip Inc., in Murietta, Calif., delves into varporizer fin design. “Beyond Counting Fins” explains how vaporizer designs differ, and that the common practice of comparing vaporizer size and performance by counting the number of fin elements can be misleading. According to Smith, vaporizer units that have an identical number of fin elements, and even the same element length, may give varying performance in terms of continuous cryogen vaporization. The variable in fin elements, he points out, includes more than just the external surface area, but also their spacing, thickness and surface finish.
In “Advanced Chiller Control” by Biagio Lamanna, thermodynamics laboratory manager in the Thermodynamics Research Department of Carel S.p.A., Brugine, Padova, Italy, compressor and water limits, and overall unit stability impact performance. Lamanna looks at a newly developed chiller system that improves control of inverter-driven compressors, electronic expansion valves and condenser fans to provide energy savings while optimizing chiller performance in a variety of operating conditions.
Ask Questions, Evaluate, Select
January 1, 2007