Experimental study on drying process of a tumble dryer and analysis of drying performance

In this thesis, an experimental investigation about the effect of drying performance on laundry dryer with different loads were studied. Therefore the experimental setup was established. This setup has water-cooled condenser different from household tumble dryers on market. In the experimental study, the effect of the amount of load to be dried, energy consumption and drying time was determined. Some measurements were made in the experimental set up, so that theoretical calculations could be made. Condensation water flow that affects the drying time is theoretically calculated by the energy and mass balances established in the condenser region. The results obtained with theoretical calculations are compared with experimental data. The amounts of deviation between the values obtained by the calculations made and the actual values were determined. Since all calculations and experimental results were instantaneously examined. Temperature changes and condensing water droplets during the drying process were instantaneously detected. These instantaneous changes were compared for analysing the characteristics of different drying loads. As a result; in accordance with the experimental studies and theoretical calculations made, the amount of water that goes out of the condensation aftertreatment system in the studied tumble dryer condenser unit is realized with a phase difference of 9 minutes according to the instantaneous calculated water amount. This phase difference is found to be approximately 9 minutes for all loads examined. In addition, the increasing the amount of load dried in the drying system causes increasing the mass flow of the condensing water. The increase in the mass flow of the condensing water reduces the drying time of the unit charge amount and the energy of the spent heater. Process air flow decreases during drying cycle because of lints that covers on lint filter surface. Theoretical condensing water flow was obtained by using the heater power, process air heater inlet-outlet temperatures, the process air condenser inlet-outlet dry and wet thermometer temperatures. Water amount calculated by water flow and time datas. And theoretical water amount was obtained with -16% difference according to the test results. This difference is at the same level in all loads examined and the model is successfully built. Similarly, the theoretical condensing water flow were reached with a 95% probability of 18-20% difference from the experimentally obtained data. Tumble dryers provide drying laundries fast, without the need for too much living space and without being affected by air pollution, air conditions and intense sun rays. The process in the tumble dryer is as follows; the air is heated. The heated air is directed onto the laundry to be dried. Finally, moisture is removed from the laundry. The air that includes moisture have some laundry lints on itselves. That lints is removed by a lint filter. The hot air takes its moisture on the laundry by evaporation. In some tumble dryers, the air heated is taken out of the dryer by means of a chimney after desiccation of the laundry. In some tumble dryers, damp air is not sent out of the dryer, the humid air is condensed and this air is regain into the drying cycle for saving energy. Besides, user's usage habits affect the user either positively or negatively. The full capacity, medium capacity or low capacity of the tumble dryer usage changes the parameters that affect the user, such as all energy consumption and drying time. Light loads were used as 2 kg, medium loads were used as 4 kg and heavy loads were used as 6 kg in this study. In this thesis, the drying performances of different loading quantities will be examined. In the experimental setup, the calculations made in the direction of this instantaneous temperature data taken during the drying process from different points and the rate of condensation, which is called condensing water flow, will be theoretically and experimentally determined. This process will be repeated with different loads and the drying rates of the different loads will be compared over the theoretical and experimental data. In this thesis, an experimetal setup was created for simulating tumble dryer. This setup which has drum, process fan, filter, electric heater and condenser, has been studied on. The condenser that used is a water-cooled. The condenser's tubes' material is copper. The condenser's cooling water flows inside these tubes. And aluminum fins in contact with copper tubes are used to increase heat transfer. Condenser cooling water refrigereates by a heat pump system. This system's hot exchanger side is located at environment. And cold side exchanger is located in a water tank that is a hundred litres. All the tests used the same components and values. Only, load quantities were changed. 6kg, 4kg and 2kg dry cotton textile load samples were used with %60 huminity. In the experimental study, the effect of the amount of load to be dried, energy consumption and drying time was determined. Some measurements were made in the experimental set up so that theoretical calculations could be made. The heater current, heater voltage and heater air inlet-outlet temperatures were measured to determine the air flow rate. In order to calculate the amount of condensing water during drying, wet-dry thermometer temperatures, condenser cooling water inlet-outlet temperatures, condenser cooling water flow and condensing water temperature were measured at the inlet and outlet of the condenser. Condensation water flow that affects the drying time is theoretically calculated by the energy and mass balances established in the condenser region. The results obtained with theoretical calculations are compared with experimental data. The amounts of deviation between the values obtained by the calculations made and the actual values were determined. Since all calculations and experimental results are instantaneously examined, temperature changes and condensing water droplets during the drying process are instantaneously detected. These instantaneous changes are compared to the characteristics of different drying loads. As a result; in accordance with the experimental studies and theoretical calculations made, the amount of water that goes out of the condensation aftertreatment system in the studied tumble dryer condenser unit is realized with a phase difference of 9 minutes according to the instantaneous calculated water amount. This phase difference is the source of the condensate droplets flowing through the fins to the water accumulation table located in the condenser sub-region. Theoretically obtained results are obtained from the instant speed of the condensation. This phase difference was found to be approximately 9 minutes for all loads examined. In addition, the increase in the amount of load dried in the drying system causes increasing in the mass flow of the condensing water. The increase in the mass flow of the condensing water reduces the drying time of the unit charge amount and the energy of the spent heater. Process air decreases during drying cycle because of lints that covers on lint filter surface. Lint amounts can vary according to the laundry properties that used. Cotton textiles were used in the tests. The amount of lint varies by washing and drying cycles the laundry. The amount of lint loosening in the laundry washed and dried for the first time is higher than the laundry used for a long time. New cotton textile was used in all tests in order to avoid this variability. Constant heater current and voltage value, increasing at heater inlet and outlet air temperature difference is determined to decrease of process air flow rate. In conclusion; the heater power, process air heater inlet-outlet temperatures, the process air condenser inlet-outlet dry and wet thermometer temperatures were obtained with a theoretical water amount of -16% according to the test results. This difference is at the same level in all loads examined and the model is successfully built. Similarly, the theoretical condensing water flow rate were reached with a 95% probability of 18-20% difference from the experimentally obtained data.