To Örebro University

Micro-CT analysis of experimentally creased and folded multilayer cardboards reveals insights into how the material deformation due to the creasing and folding process of cardboard impact the material concerning delaminations and position of broke particles. Delaminations were found in various locations and varied in size from just under a tenth of a millimeter to up to four times the thickness of the cardboard. The particles varied in size, ranging from a few micrometers to slightly larger than the cardboard thickness. Characteristic dimensions for the creased and folded cardboard were measured for selected cross sections. The differences in characteristic dimensions for the cross sections among the samples were typically a few hundredths of a millimeter. There are differences between cross-sections that are a few hundredths of a millimeter apart.

Carton board packages with different creases have been manufactured and loaded with point loads to see if there is a difference in point load behavior depending on crease. A carton board was creased in four different ways. The differences of the creases were judged according to appearance and residual moment. Three of the four creases showed divergent appearances. The re-sidual moment was as expected lowest for the hardest creased sample and vice versa. The packages with the different creases were loaded with a point load. The registered force - displacement curves were analyzed according to stiffness and collapse load. No statistically significant difference could be seen in the collapse load of the package or in the stiffness measured, indicating that with a standard point load measurement it was hard to distinguish a difference in packaging behavior due to creasing. In future work it might be interesting to further study the average stiffness, since a trend of higher average stiffness for lower matrix channel depth exists in the measurements, however not statistically ensured. One possibility to discern possibly existing differences in the resistance of packaging to point load due to crease differences could be to study the interaction in more detail.

The perception of mechanical rigidity when touching a package is important for purchasing decisions. This perception will depend both on the material and geometry of the product packaging, but also on the position where the package is grasped. Both kinaestethic (globally) and cutaneous cues (locally around the fingertip) play a role in the perception of compliance, but cutaneous cues are more important. We therefore use a tactile sensor to investigate the mechanical interaction between the tactile sensor and a cartonboard package; we study the changes depending on the measuring position and the material. Using linear discriminant analysis (LDA) on the measurement result we show that we can separate these two changes for separate analysis.

The importance of sensory information in product purchasing decisions has gained increasing attention in recent years. Tactile properties of packaging are usually measured with the help of trained evaluators. An objective, fast and repeatable method that describes the mechanical interaction and does not rely on a panel would have many benefits. We propose and evaluate such a method for measuring the mechanical interaction between a deformable finger-like shaped sensor and a package. Evaluation of the method shows good repeatability, the variability in the measurement result is within a few percent in most cases. The method captures indentation differences at contact between sensor and package due to measurement position and package design.

This work reports the evaluation of a tactile sensor for the potential of using it to measure the compliance of folding cartons. A tactile sensor would make it possible to measure the mechanical behavior locally around the contact point, in contrast to existing methods that measure the global mechanical behavior of the carton. Research on the haptic sense has shown that the local mechanical behavior is more important than the global behavior when humans assess compliance of objects. It is shown that the response of the tactile sensor correlates strongly with the bending stiffness of the board, but also with geometric features. A method for reducing the 22-dimensional output of the sensor to single meaningful feature using linear discriminant analysis is proposed and tested. The results show that the sensor is a good candidate for a method that incorporates both cutaneous and kinaesthetic information in the measure of carton compliance.

A method for calculation of long-term heat losses from polyurethane foam insulated twin pipes is presented, accounting for the spatial dependence and time variation of the insulating capacity of the foam. With aid of a coordinate transformation the cross-section of the twin pipe is mapped onto a rectangular geometry, which facilitates the modeling. Preliminary results given by the new model are compared to results given by a previous model.

Goal, Scope and Background. The idea of district heating is to transport centrally produced heat to buildings where it is used for space heating and for domestic hot water generation. Water is used as a heat carrier. Many different heat sources are used to supply district heating networks with hot water. In literature, environmental studies on district heating mainly consider emissions from the heat generation; environmental impacts from the distribution system are seldom discussed. This paper is the third in an article series on the environmental impacts from the district heat distribution system. The paper presents an evaluation of the use phase of district heat distribution, focusing on long-term thermal performance of different district heating pipes. An overall discussion, in which environmental impacts from the different life cycle phases of district heat distribution are compared, is also presented.

Methods for the Use Phase Study. Environmental impacts from use of district heat distribution systems were evaluated based on heat losses from the networks, which depend on the long-term thermal performance of the district heating pipes. The heat losses cause environmental impacts from extra heat generation needed to cover the losses.

The long-term thermal performance of preinsulated bonded district heating pipes with steel tube, polyurethane foam insulation and polyethylene casing, depends on the thickness and quality of both the insulation and the casing. One important attribute of the foam is the blowing agent used. The blowing agent influences both the initial insulating capacity of the foam and the ageing characteristics, due to differences in migration rates of different substances through the materials.

Heat losses were calculated for different district heating pipe dimensions (DN25 twin pipe, and DN25, DN100 and DN500 Series 2 single pipes). Pipes with two different foam blowing agents (cyclopentane and carbon dioxide) were studied, taking into account the differences in long-term thermal performance of the foams. Concerning emissions from heat generation, two heat sources were considered: heat generation according to the average district heating fuel mix used in Sweden in the year of 2000, and heat generation using natural gas heat only boilers. The functional unit used is 100 m of district heat distribution network during 30 years of use.

Results and Discussion on the Use Phase. A short description of the inventory, some inventory results and a life cycle impact assessment are presented. Characterizations according to GWP, AP, POCP and resource depletion are given as well as two weightings: EcoIndicator99 and Ecoscarcity. The DN25 twin pipe network has about 25% lower environmental impacts from use than the DN25 Series 2 single pipe network. The district heating pipes insulated with cyclopentane blown polyurethane foam have a better environmental performance during use compared to those insulated with carbon dioxide blown foam (6-13%). This is partly dependent on a higher initial insulating capacity of the cyclopentane blown foam, but also due to a slower deterioration of the insulating capacity over time. For the two heat sources considered, different impact assessments give different indications to which option that is environmentally preferable.

Overall Results and Discussion on Pipe Production, Network Construction and Network Use Phases. A comparison of the three life cycle phases studied in this article series was made concerning four emissions, the four characterizations and the two weightings. The use phase represents over half of the total environmental impact for most, but not all, environmental parameters studied. It is important to keep the heat losses from the network down and to strive for heat sources with low environmental impacts. The larger the pipe, the larger is the relative impact from pipe production. The network construction phase has a relatively small contribution to the total environmental impact in most systems studied. However, the emissions during network construction often occur in residential areas and may therefore not be neglected when immediate nuisances and health aspects are considered. A very small change of the material flows in the production phase, the change between two different blowing agents (cyclopentane and carbon dioxide), can give dramatic results for the total environmental outcome for the district heating network because of a large change in influence on environmental impacts during use. The DN25 twin pipe network proves to be environmentally advantageous compared to the DN25 Series 2 single pipe network during all of the studied life cycle phases. Recommendations and Perspectives. It is important to make sure that improvements in the production and construction phases do not lower the insulating capacity of the district heating system. A good initial insulating capacity, maintained over time, is important for the environmental performance of a district heat distribution network. Using DN25 twin pipes instead of DN25 Series 2 single pipes is a better choice, when possible, regarding all studied life cycle phases. The environmental impact from use of the district heat distribution system depends heavily on the type of energy source that is utilized to supply the network with heat.