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Nosemount Diesel-Electric Chiller
Boalloy - the innovative semi-trailer manufacturer - produced an insulated version of their "Tautliner" curtain wall vehicle for the developing chilled distribution market. While an insulated version had been developed, heat inleakage exceeded that for rigid bodies. Conventional HGV semi-trailer refrigeration units were over-worked in the application, so that breakdowns were frequent.
The British Design Council appointed us as design engineers and project managers to produce a machine that would encourage global manufacturers to meet the higher duty requirement. It should also obviate problems commonly encountered in the design and operation of HGV nosemount chillers. Refrigerant leakage was a persistent nuisance, originating from shaft seal wear in conventional direct-coupled drives. Widespread complaints of excessive noise emission were directed toward operators, particularly concerning loaded vehicles parked overnight. Once installed onto a host trailer, units could not readily be transferred to others in a fleet, nor employed on related applications
We addressed these issues through thermal testing and modelling of curtain-wall bodies, embodying semi-hermetic equipment to obviate drive leakages, optimizing noise emission by designing and building a compact diesel generator (driven by a newly-developed lightweight diesel engine), and incorporating quick-release mountings for easy transfer to other vehicles. This prototype diesel-electric chiller was run daily for a year between London and Aberdeen for test purposes, requiring only engine oil and filter service. It was then retired for reference as paradigm for subsequent industry-standard designs of HGV nosemount chillers.
Special-Purpose Chillers
GEC Alsthom needed to emulate domestic production at its Indian subsidiary. Temperatures could not be attained without refrigeration, and the process load was variable. A simple, easily maintained and compact design was prerequisite for the crowded factory floor, and the host process had to be accommodated with a high degree of accuracy. While the original custom chillers were built as shown in the photograph, we provided drawings and manuals for local production when further units were required.
Dove Thermal has designed various industry-specific special purpose chillers for third party manufacture. A major offshore contractor - Chorley Engineering - needed a transportable glycol chiller for rig operations. We designed a range of enclosed cradle semi-hermetic custom chillers for easy handling and low maintenance, which were then built at their Atherstone base. Following rigorous performance trials, this was established as the corporate design standard for similar machines.
While a small fridge plant might respond readily to varying loads, it becomes desirable to reconcile capacity and demand more economically as heat flows increase. For example, we build special purpose chillers incorporating baffled buffer tanks to serve applications cycling to several times their rating. By smoothing-out peaks and troughs between process load and machine rating, push-pull flow across one of our coolant management modules matches refrigeration capacity with system demand. It presents the chiller with a relatively constant load near to its design point, so that the machine runs at best available efficiency at a steady - but much smaller – loading.
Dove Thermal Engineering Limited, Uttoxeter, ST14 8QX
Telephone: 01889 569933