Skapa förutsättningar för att implementera Lean production i en tillverkningsprocess som kännetecknas av HVLV : - En fallstudie på Tibrokök Sverige AB

Idag är det vanligt att företagen konkurrerar med produkter som innefattar en fysisk vara som har utvidgats med olika tjänster för att kunna tillfredsställa kundens behov. I takt med detta ökar produkternas komplexitet och högre krav ställs på leverantörerna. Denna utveckling har lett till att många företag som tillverkar produkter med hög variation måste arbeta helt kundorderstyrt för att kunna tillgodose kundernas ökande krav. Företagen som tillverkar dessa komplexa produkter har en tillverkning som karaktäriseras av hög variation och låg volym vilket benämns med förkortningen HVLV. Utmaningen för dessa HVLV-företag ligger i att ha en hög produktmixflexibilitet med så låg resursanvändning som möjligt. För att effektivisera verksamheten har många företag därför intresserat sig för Lean production som har visat sig vara ett framgångsrikt koncept för tillverkande företag runt om i världen som effektiviserat sin produktion. Ett flertal artiklar har uppmärksammat begränsningar vid implementeringen av Lean production i HVLV-miljöer. Artiklar pekar vidare på behovet av ytterligare forskning kring Lean productions applicerbarhet i HVLV-miljöer och detta var uppkomsten till examensarbetets bakgrund och syfte. En fallstudie har genomförts på Tibrokök som är ett företag med en helt kundorderstyrd produktion som kännetecknas av HVLV. Med hjälp av fallstudien syftar examensarbetet till att undersöka om verktygen processkartläggning inkl. tidsstudier och layoutflödesdiagram kan bidra till att skapa förutsättningar för implementering av Lean production i en enskild tillverkningsprocess i en HVLV-miljö. Trots att verktygen har behövt anpassas något så anses de ha varit användbara och bidragande till skapandet av förutsättningar för implementering av Lean production i denna HVLV-miljö. Detta eftersom vi kunde identifiera många orsaker till slöseri samt ta fram ett förslag som skapar effektiviseringar av Tibroköks ytbehandlingsprocess i det framtida läget.

Techno-economic analysis of three HVAC retrofitting options

Accounting for around 40% of the total final energy consumption, the building stock is an important area of focus on the way to reaching the energy goals set for the European Union. The relatively small share of new buildings makes renovation of existing buildings possibly the most feasible way of improving the overall energy performance of the building stock. This of course involves improvements on the climate shell, for example by additional insulation or change of window glazing, but also installation of new heating systems, to increase the energy efficiency and to fit the new heat load after renovation. In the choice of systems for heating, ventilation and air conditioning (HVAC), it is important to consider their performance for space heating as well as for domestic hot water (DHW), especially for a renovated house where the DHW share of the total heating consumption is larger. The present study treats the retrofitting of a generic single family house, which was defined as a reference building in a European energy renovation project. Three HVAC retrofitting options were compared from a techno-economic point of view: A) Air-to-water heat pump (AWHP) and mechanical ventilation with heat recovery (MVHR), B) Exhaust air heat pump (EAHP) with low-temperature ventilation radiators, and C) Gas boiler and ventilation with MVHR. The systems were simulated for houses with two levels of heating demand and four different locations: Stockholm, Gdansk, Stuttgart and London. They were then evaluated by means of life cycle cost (LCC) and primary energy consumption. Dynamic simulations were done in TRNSYS 17. In most cases, system C with gas boiler and MVHR was found to be the cheapest retrofitting option from a life cycle perspective. The advantage over the heat pump systems was particularly clear for a house in Germany, due to the large discrepancy between national prices of natural gas and electricity. In Sweden, where the price difference is much smaller, the heat pump systems had almost as low or even lower life cycle costs than the gas boiler system. Considering the limited availability of natural gas in Sweden, systems A and B would be the better options. From a primary energy point of view system A was the best option throughout, while system B often had the highest primary energy consumption. The limited capacity of the EAHP forced it to use more auxiliary heating than the other systems did, which lowered its COP. The AWHP managed the DHW load better due to a higher capacity, but had a lower COP than the EAHP in space heating mode. Systems A and C were notably favoured by the air heat recovery, which significantly reduced the heating demand. It was also seen that the DHW share of the total heating consumption was, as expected, larger for the house with the lower space heating demand. This confirms the supposition that it is important to include DHW in the study of HVAC systems for retrofitting.

Produktion, skador och grenegenskaper hos 10-årig tall i ett kombinerat förbands- och avkommeförsök : Volume production, damages and branch properties in a 10-year old combined spacing and progeny trial of Scots pine

A Scots pine (Pinus sylvestris) progeny trial was established in 1990, in the southwestern part of Sweden. The offspring was from 30 plus trees. The trial is located on abandoned agricultural land and has a single tree block design with a variation in spacing. The trial has been damaged by voles. At a tree age of ten years, growth, damages and branch properties were estimated. An analysis of variance on height, diameter and stem volume shows significant difference between spacing and progenies as well as interactions between these factors. As indicated by a better annual height increment and fewer and thinner branches at each whorl the densest spacing has the highest potential to produce quality logs.There were also differences between progenies in growth and quality traits. Some progenies combined good growth and branch characters with low mortality, straight stems and few damages. Other progenies had superior volume production.

Performance evaluation of ventilation radiators

A ventilation radiator is a combined ventilation and heat emission unit currently of interest due to its potential for increasing energy efficiency in exhaust ventilated buildings with warm water heating. This paper presents results of performance tests of several ventilation radiator models conducted under controlled laboratory conditions.   The purpose of the study was to validate results achieved by Computational Fluid Dynamics (CFD) in an earlier study and indentify possible improvements in the performance of such systems. The main focus was on heat transfer from internal convection fins, but comfort and health aspects related to ventilation rates and air temperatures were also considered.   The general results from the CFD simulations were confirmed; the heat output of ventilation radiators may be improved by at least 20 % without sacrificing ventilation efficiency or thermal comfort.   Improved thermal efficiency of ventilation radiators allows a lower supply water temperature and energy savings both for heating up and distribution of warm water in heat pumps or district heating systems. A secondary benefit is that a high ventilation rate can be maintained all year around without risk for cold draught.

Energy efficient and economic renovation of residential buildings with low-temperature heating and air heat recovery

With the building sector accounting for around 40% of the total energy consumption in the EU, energy efficiency in buildings is and continues to be an important issue. Great progress has been made in reducing the energy consumption in new buildings, but the large stock of existing buildings with poor energy performance is probably an even more crucial area of focus. This thesis deals with energy efficiency measures that can be suitable for renovation of existing houses, particularly low-temperature heating systems and ventilation systems with heat recovery. The energy performance, environmental impact and costs are evaluated for a range of system combinations, for small and large houses with various heating demands and for different climates in Europe. The results were derived through simulation with energy calculation tools. Low-temperature heating and air heat recovery were both found to be promising with regard to increasing energy efficiency in European houses. These solutions proved particularly effective in Northern Europe as low-temperature heating and air heat recovery have a greater impact in cold climates and on houses with high heating demands. The performance of heat pumps, both with outdoor air and exhaust air, was seen to improve with low-temperature heating. The choice between an exhaust air heat pump and a ventilation system with heat recovery is likely to depend on case specific conditions, but both choices are more cost-effective and have a lower environmental impact than systems without heat recovery. The advantage of the heat pump is that it can be used all year round, given that it produces DHW. Economic and environmental aspects of energy efficiency measures do not always harmonize. On the one hand, lower costs can sometimes mean larger environmental impact; on the other hand there can be divergence between different environmental aspects. This makes it difficult to define financial subsidies to promote energy efficiency measures.