Heat pump design for timber drying
Whilst working at the University of Otago, Dr Eric Scharpf and Professor Gerry Carrington decided to engage in a novel heat pump design project. Instead of improving the world with new science, they shifted their focus to improving the world with new ways to engineer existing science. They intended to better use existing science and existing engineering on existing problems.
Designing heat pump dehumidifiers
Dr Eric Scharpf, an energy management expert, has experience in the design and construction of heat pump dehumidifiers for industrial use in timber drying. In this video, he explains how, working with Professor Gerry Carrington, a radical design was developed and taken through to a marketable product.
Improved timber-drying process
The project was based around how to use heat pumps to move energy around more intelligently, with a particular emphasis on timber-drying kilns. A huge amount of timber is processed in New Zealand for both the domestic and overseas markets. Improving the efficiency of the timber-drying process would not only keep costs down but also produce a better product.
Dr Eric Scharpf
Dr Eric Scharpf discussing the energy efficiency of heat pump dehumidifiers with students in a postgraduate energy management class.
The experimental phase of the project involved arranging heat pump components in very unusual configurations in the circulating heat flow in the timber dryer and analysing the heat transfer and moisture removal characteristics. In addition, by incorporating temperature, humidity and airflow sensors at key points in the kiln and linking these to a master control system, the operation of the heat pump was carefully controlled.
Marketing the design
After successfully completing the experimental and design calculation phases, Eric and Gerry set about marketing the design variations they had investigated. They set up a company, Delta S Technologies Limited, to service industries, such as timber processing, that required a drying or dehumidifying function as part of their operation.
Timber outside kiln
A stack of timber sits outside a traditional drying kiln, in a Dunedin Lumber yard.
For example, with a timber-mill customer, a thorough analysis of the timber-drying operation was undertaken. The data collected was run through numerous calculations matched against specific pieces of heat pump and control systems equipment performance estimates. The optimal equipment was then purchased, installed and trialled. Once operational, the system was able to dry timber more evenly, producing a better finished product at lower cost.
Unfortunately for Delta S Technologies Limited, the sales and marketing of the family of heat pump dehumidifiers proved to be difficult. Although the designs combined current scientific understandings of moving energy around with state-of-the-art technological and engineering advances in control systems, the stormy ocean of the world economy took its toll. Events as diverse as a change in Russian tax law on their export timber, a beetle infestation in Canada and the US housing market collapse changed the way billions of dollars of timber moved around the world. As a result, New Zealand timber companies suffered a downturn, forcing a cut-back on production as well as plant and equipment upgrades. Eventually, Delta S Technologies ceased to operate as a company, but its timber kilns continue to dry timber better and more efficiently at a number of sites throughout New Zealand.
Heat pump design variations
The hard work that Eric and Gerry put into the project has not been lost. Along the way, a number of aspects of the special heat pump design variations have been patented and are now available in the public domain. In addition, the broader knowledge gained from the scientific, technological and engineering perspectives is recorded in the literature and resides there to be used at a future date.
