Investigation into improving Efficiency in a Domestic Drying Process

Abstract

This thesis investigates the methods of improving efficiency in a domestic drying process. The ‘Six Sigma’ statistical techniques were followed extensively for all the experimental works. A review of several common drying technologies is provided, together with methods of improving energy efficiency of the drying process. Energy efficiency and labelling in the laundry industry have been investigated. The market trends and principle of the condenser tumble dryer are also discussed. A mathematical model of the condenser tumble dryer has been generated to determine the potential opportunities for improving energy efficiency. The ‘Six Sigma’ analysis techniques have been the main structure of this project. ‘Six Sigma’ analysis is a mathematical model that analyse data statistically. The Critical-to-Quality (CTQ) flow chart was used to identify the major factors of the project. The Design-of-Experiment (DoE) was used for generating energy test specifications and analysing the results. The DoE tool was used to generate an energy test specification to satisfy the European testing standard. The results of the DoE energy test have suggested the final moisture content is the most important factor to energy efficiency. The average energy performance of the condenser tumble dryer has been established from the results of the baseline energy tests. These results also indicated the level of improvement required to achieve a ‘B’ rated energy efficient condenser tumble dryer. Intrusive measurements were performed in three specified condenser tumble dryers selected from the baseline energy tests. The air conditions at different stages of the drying process were recorded during the intrusive measurement. The relationship between energy consumption and air condition of the three condenser tumble dryers has been established. The factor levels of the condenser test rig DoE have also been identified from the intrusive measurement results. The Creda condenser unit has been tested extensively with different inlet air condition by utilising the condenser test rig. A condenser test rig test specification was generated using previous data and the ‘Six Sigma’ DoE tool. The results of this condenser test rig DoE were then used to generate an advanced model of the DoE, which is the ‘Response Surface DoE’. The results of the response surface DoE have identified the optimal operating condition within the existing capability of the condenser tumble dryer. The whole drying cycle of the condenser tumble dryer is discussed towards the end of this thesis. Several techniques were used to investigate different parts of the condenser tumble dryer assembly. A CFD model has been generated to analyse the airflow at the heater and fan assembly. The drum assembly was intended to be tested by a drum test rig and using the DoE technique. Different condenser units were tested in the condenser tumble dryer and the condenser test rig enabled identification of potential improvement opportunities.