Investigation of mechanical losses in laundry drying machines and optimization of bearing system

Nowadays, the wise use of energy is getting more important every day. As a result, the studies aiming to reduce the energy consumption in the white goods sector are becoming more intense. The usages of new generation of laundry drying machines are increasing in modern life. Therefore, the optimization of the bearing system and the improvement of the energy consumption accordingly constitute the main objective of this study. Despite its use at the beginning of the 20th century, tumble dryers have become widespread in Turkey in recent years and have created a new sector. Especially the transition from rural settlements to urban settlements brought together houses with small or no balcony. In urban life, drying laundry in open areas like balconies creates visual pollution and causes some problems in areas where air pollution is high. In addition, low temperatures in the winter months make it difficult to dry clothes in the open-air environment, such as balconies. Laundry drying machines adapt to the new city life and at the same time generate significant timesaving. General functions of drying machines; after the washing process, drying the moist laundry with the help of hot air in a rotating drum rotating at low speed. Because they do not even require ironing after drying, these machines adapt to the new apartment life and provide a significant time saving. Most of the energy resources used for electricity generation in the world are fossil fuels such as oil, natural gas and coal. The global warming threat, which is increasingly caused by the carbon emissions of fossil fuels, necessitates reducing energy consumption as well as changing energy sources. In recent years, the concerns about energy resources in the world have brought certain energy consumption constraints in the white goods sector as well as in many sectors. For this reason, the low amount of energy consumed by a machine creates an economic and global advantage. Annual energy consumption per capita in Turkey is 3373 kWh in 2015. This value is 3060 kWh worldwide for 2015, 13000 kWh in the US, 7750 kWh in Japan and 5500 kWh in Europe. This value, which is high in developed countries, is also rapidly increasing in developing countries like Turkey. In order to reduce the electricity usage of the consumers, we must inform the consumers about this and provide products with low energy consumption. For this reason, it is important to increase the efficiency of white goods machines, which are frequently used in everyday life. Energy classes are divided into 7 classes as A +++, A ++, A +, A, B, C and D. Class A represents the most productive class and energy efficiency is being improved by reducing energy consumption day by day. The main purpose of this study is to determine the mechanical losses of laundry dryer machine with energy efficiency of A class and to reduce the energy consumption by optimizing the bearing system of drum. The energy efficiency coefficient (EEI) is used to determine the energy classes of the drying machines. This coefficient is calculated according to the electrical energy consumed by the machine in the drying test, which is done with the conditions specified in the relevant regulation. The study shows how the energy efficiency coefficient (EEI) is calculated. Reducing the energy consumption has reduced this value so that the energy class of the drying machine has been increased. Before starting to work, the types of tumble dryer are shown and the working principle of each type is explained. In addition, similar studies were investigated by literature review. The patent applications relating to the improvement of the existing bearing system in the tumble dryer have been found and examined before the study. In drying machines; the drive system consists of motor, drum, drum bearing and belt-pulley system used for power transmission. The motor has been excluded from the study due to the fact that the motor has a certain efficiency in working conditions. Inspection of the drive system is started with the belt-pulley system and then continued with drum, drum bearing and sealing elements. The entire system is driven by the engine mounted on the chassis with a rotational speed of 2900 rpm. The rotation motion of the motor output shaft is transmitted by a two-stage belt-pulley mechanism to rotate the drum at a speed of 54.2 rpm. On the front side, the drum is mounted with two wheels. On the rear side, the drum is bedded with a spherical bearing. In addition, there are two separate sealing elements in the tumble dryer to prevent the process air from escaping out of the system. One of the sealing elements is in contact with the front of drum and the other is in contact with the rear of drum. Some of the energy used to spin the drum goes to the elements in the drive system and some to the seal elements. The study examined the belt-pulley system. The contact angle of the drum belt, the forces generated in the belt arms and the belt slip rate were calculated. In particular, the forces acting on the drum are found by the presence of the forces that occur in the belt arms. In another part of the study, the drum system was examined. Some assumptions were made to establish the force balance for the drum and the forces coming into the drum bearing were calculated. This calculation was made for both frictionless and frictional balance. Friction moments acting on the drum were then calculated. Thus, it was found that 43% of the rotational torque transferred to the drum was spent on the bearing system and 57% of the torque transmitted to the seals. Experimental studies have found the power value used in the drive system. Then, in tests carried out by removing the front and rear seal members separately from the tumble dryer, the force exerted on both seal members was found. The power spent on both sealing systems is up to 60% of the power required to spin the drum. The remaining 40% is estimated to be spent on bearing elements. Both the calculations made and the experimental work have shown that the greatest energy losses in the drum system occur in the sealing elements. However, since the sealing elements are excluded from the scope of the study, this loss is not focused. In addition to improving the sealing system to reduce mechanical losses, it has been found that improving the bearing system is the second most important point. It is theoretically calculated that 43% of the moment transmitted to the wheel is spent in the bearing system. It is estimated that 2% of this loss is in the rear bearing and 41% in the front bearing. It has been estimated that 26% of the loss in the front bearing is in the right wheel and 15% in the left wheel. It has been seen that the right wheel has an approximately 11% greater friction loss than the left wheel. This difference is caused by different wheel positions. It has been calculated that different reaction forces are generated at different wheel positions and the frictional torque acting on the wheel changes. With these calculations made for front bearing, it is predicted that the friction torque generated on the drum will be reduced by optimizing the wheel positions. Thus, the mechanical energy consumption of the laundry drying machine will be reduced. A prototype apparatus which can be attached to the front bearing zone was built to confirm the theoretical calculations. This apparatus allows the wheel positions to be changed. With this apparatus, the wheel positions can be changed easily. In the light of theoretical calculations, experiments were conducted for different wheel positions and the energy consumption of the tumble dryer was measured. Given the available space required by the construction boundaries, there is a limited area where the wheel positions can be changed. It has been found that the wheel positions providing minimum energy consumption in this area should be 48 ° angle of the vertical position of the left wheel position and 22.5 ° angle of the right wheel position with the vertical position. Optimization of the wheel positions has resulted in an improvement of 3% in mechanical losses for the recommended position (48 ° of the angle of the left wheel with the vertical and 22.5 ° of the angle of the right wheel with the vertical). This improvement provided a 2% improvement in the weighted average energy consumption of the drying machine. On the other hand, as expected, the weighted average program time did not change. The energy efficiency coefficient (EEI) is 21.5 before the study and the energy class of the machine is A +++ (-10%). Energy efficiency coefficient (EEI) has been 21 with improvements made. Thus, the energy class is increased to A +++ (-12.5%). The study, which is intended to be applied to machines with a low energy class, provides an annual energy gain of 10 kWh in a class B dryer machine. The implementation of the improvement work has been considered to be applied to approximately one million tumble dryer machines. Assuming an average improvement of 10 kWh for these machines of different energy classes, a total improvement of 10 million kWh per year has been achieved. If we think that the annual per capita energy consumption of the world is 3060 kWh, the improvement to be made will meet the annual energy requirement of about 3270 people. In other words, a monthly energy requirement of about 39200 people can be met. In order to ensure efficient use of energy, annual energy consumption per person can be reduced by many more studies such as reduction of mechanical losses and reduction of energy consumption in the drying machines described in this study.