Produktutveckling och prestandatest av ett vattenvärmedrivet torkskåp : Jämförelse mellan tre utvecklade versioner av ett vattenvärmedrivet torkskåp

Sammanfattning: Abstract Electricity consumption is a globally increasing problem caused by the high share of electricity produced in coal power plants. These contribute to high carbon emissions when only about 1/3 of the heat generate electricity and the remaining 2/3 of the heat cools off. Combined heat and power plants (CHP) have high efficiency because they use the residual heat for domestic heating. The CHP plant often use fuels from renewable resources, giving them a lower carbon footprint, but are also depending on the heat demand. If electric powered products such as drying cabinets convert to heat powered products more environmentally friendly electricity will be produced by CHP plants, which can supplant electricity, produced from coal power plants and reduce carbon emissions. Karlstad University has therefore, in collaboration with Nimo-verken AB and Asko Appliances AB developed a prototype of a water heated drying cabinet. The prototype has been tested, evaluated and further developed into a competitive product to market. Three versions (A, B and C) of the cabinet were tested with water flow temperatures of 55 and 80 °C and was also tested half-and fully loaded. Version A's low air flow gave long drying times and poor energy efficiency (SMERTot). Version B had a better flow and therefore gave better results in drying times and efficiency (SMEREl and SMERTot). The redevelopment of Version C mounted a larger fan which markedly increased airflow in the cabinet. This version gave the best stability, drying time and SMERTot. Both the drying times and SMER Tot was better than any comparable drying cabinet on the market. The energy efficiency, proportion of electricity used for drying (SMER El) gave values several-fold higher than any comparable drying cabinets on the market. The water heated drying cabinet produced, with the conditions above, 4% of the carbon emissions for a comparable, electric-powered cabinet. To study how to stop a drying process at the right time temperature measurements were made at the exhaust air from the cabinet. Strong correlation was found for the selected water flow temperatures and versions. The conclusions were that the drying process in a drying cabinet can be stopped in time by continuous measurement of exhaust air temperature. The relatively cool supply air temperatures obtained from the hot water also manage to dry textiles quickly and efficiently if only the air flow is large enough. This also means that carbon emissions were low. The goals were achieved but there is still great development potential in flow optimization and heat loss reduction of the water heat powered drying cabinet.