Prestudy of a Power Management of a Cut-To-Length Forest Harvester with a Hydraulic Hybrid System

Abstract

A Cut-To-Length (CTL) forest harvester is used for felling, delimbing and bucking of the tree stems as forwarder is used to forward the logs cut to length to roadside landing for highway transport to the refining facilities like saw-and pulp & paper mills. Fuel consumption of forest harvesting operation is becoming a more and more important cost factor as the fuel prices are raising constantly. A number of studies exist on various hybrid systems related to on-& off-highway vehicles and work machines. This paper deals with technological possibilities and potential to cut down fuel consumption of a CTL harvester by implementation of a hydraulic hybrid system that is mainly designed to take care of the highest power demands. In order to be successful in this aim, a detailed analysis of the work cycle and present power management and transmission systems are needed. Engine load data together with relevant Arcnet and CAN bus messages as well as needed hydraulic system parameters are logged during actual work in order to understand the actual nature of the application in terms of work cycle. This study is focusing on a hydraulic hybrid system, as it seems to be an applicable solution to mobile work machinery in question. Howevera background review of other hybrid solutions is also given. Some of the relevant advantages of a hydraulic hybrid system in forest machine application are also explained in this paper. Based on the prestudy and analysis on the work cyclea promising potential for hydraulic hybrid system can be seen in a CTL harvester. Future work to be done is proposed to include simulations to make a more detailed dimensioning of the components and design of the system possible already before building an actual test setup.

Battery Technology

“…Grinders and chippers operating at industrial sites can be powered with electric engines while machines operating at terminals, road side landings or logging sites are run using diesel engines (Di Fulvio et al 2015). A third option is to use hybrid systems, which store excess energy from the diesel engine during low periods of loading for use during peak loading times (Sun et al 2010, Einola 2013, Eriksson et al 2013, Di Fulvio et al 2015).…”

“…The power demand from the prime mover is typically highly dynamic in wood chipping and for this reason the diesel engines typically need to be dimensioned for a much higher maximum power than the average chipping work load. Furthermore diesel engines typically have their most fuel efficient working point in lower rpm range, where the highest nominal power is not available, which increase the fuel consumption during peak loading times (Einola 2013). Fuel costs are 30-33% of total comminuting costs (Laitila et al 2015b) and fuel prices have been rising remarkably (Einola 2013).…”

“…Furthermore diesel engines typically have their most fuel efficient working point in lower rpm range, where the highest nominal power is not available, which increase the fuel consumption during peak loading times (Einola 2013). Fuel costs are 30-33% of total comminuting costs (Laitila et al 2015b) and fuel prices have been rising remarkably (Einola 2013). Therefore more and more interest to novel solutions reducing the fuel consumption is brought to discussion and hybrid systems capable of evening out the power peaks of the work cycle are of great interest among machine manufactures.…”

Improving performance and energy efficiency of biomass supply through machine alteration and organisational redesign

“…Hybrid systems are a good example of machine developments which offer an alternative to purely electric or diesel operations. Hybrid systems are systems that can use more than one power source, although typically only a single primary power source exists (Einola 2013). Immonen (2013) stated that through electric hybridisation, the energy efficiency of diesel-driven working machines can be improved, since for most of the working time diesel engines operate at poor efficiency.…”

“…Immonen (2013) stated that through electric hybridisation, the energy efficiency of diesel-driven working machines can be improved, since for most of the working time diesel engines operate at poor efficiency. Hybrid systems, instead, are capable of storing excess energy generated by the diesel engine during periods of low loading for use during peak loading times (Sun et al 2010, Einola 2013, Eriksson et al 2013, Di Fulvio et al 2015. Additionally, with the right combination of parameters and machine setup, the operational efficiency of the entire supply chain can increase (Röser 2012).…”