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R402 Inverter Use, Air Delivery and Crop Quality

Publication Date: 
24 August 2011
Author/Contact :
Author/Contact: 
Adrian Cunnington

Contractor :
Contractor: 
SBCSR

Full Research Project Title: Assessment of the impact of inverter use in relation to store performance, with particular reference to changes in the dynamics of air delivery to the crop and associated effects on potato quality.
Duration: October 2007 - September 2010

Aim: To provide independent data on the impact of airflows, particularly in relation to the use of inverters, in relation to store performance with particular reference to changes in patterns of air delivery to crop and associated crop quality. 

Industry Challenge

Applied research and commercial evaluations in the UK and overseas have shown that inverters can offer potential benefits in terms of enhanced chemical application and lower energy use in potato stores. However, what is not at all well understood is the impact of their use on the effectiveness of the store’s ventilation system as slowing fan speeds is taking the ventilation system outside previously-adopted limits. Reductions in fan speed are likely to affect weight loss, air penetration and distribution but there is no data available to assess the impact of these changes on the store performance and, ultimately, the crop.

Collaboration

SBCSR, Crop Systems

Approach

A minimum of 6 commercial stores was studied each storage season. Airflows and pressures over the range of settings used on the inverter were measured. Measurements of airflows collected during the season were used in conjunction with commercial assessments of crop quality to determine the impact of inverter use in relation to store performance, with particular reference to changes in the dynamics of air delivery to the crop and associated effects on potato quality.

Key Findings

Reduction in fan speeds resulted in a linear fall in air delivery in this study across the full range of inverter use from 15 -100% of full speed in six bulk stores which were assessed in 2007/08. However, in 2008/09, when stores were loaded more fully with wetter and dirtier crop so back pressure was therefore increased - this linear response was less evident. Fan performance at higher speeds tended to tail off at speeds beyond 75% of maximum air delivery rate. An inverter allows demand and supply for air to be matched by changing the speed of the fan. Reducing fan speed can give a proportionately higher saving on electricity use and this was confirmed in this study. However, the optimal level of savings when considered in relation to air delivery was achieved with the inverter set to allow the fan(s) to run at around 75% of its full speed.

Recommendations

It is recommended that potential users of inverters seek specialist advice before installing systems so that they can be guided in their use to optimise savings whilst avoiding any difficulties which might be associated with their use in specific storage situations.

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