Type of yarn and counts affects energy consumption
The amount of energy consumption for different types and counts of yarn was calculated in the same way and the results obtained are shown on Energy consumption for machines and compressed air page. The finer yarn needs more energy consumption for all types of yarn. Yarns used for weaving involve more twist than yarns used for knitting and production speed is low for weaving yarn and as a result, with the same count more energy is consumed for weaving yarn. Also, for the same count, the energy consumption for combed yarn is higher because of the additional production step (combing). Specific energy consumption of 20 tex combed weaving yarn is recorded as 3.64 kWh/kg whereas; the calculated consumption in the present study takes the value of 3.32 kWh/kg for the same yarn. It appears that the differences in manufacturing parameters cause this discrepancy.
Energy consumption for ring spinning machine
Since the highest energy consumption occurs in spinning machines during yarn manufacturing, many studies have been carried out on the energy consumption of spinning machines. One of the studies shows that specific energy consumption in a ring spinning machine, ER (kWh/kg), can be calculated by the equation given below
where; F is the linear density of yarn (tex), Dr is the diameter of the ring (m), n is the speed of spindle (1000 r.p.m.) and a tex is the twist factor of the yarn. The production parameters of 20 tex combed yarn of which the total energy consumption is calculated in the present study are n = 17500 r.p.m., a tex = 3828 (ae = 4) and Dr = 0.04 m. If these parameters are evaluated in the equation (10), the specific energy consumption of ring machines is found as 1.36 kWh/kg. As can be seen from Table 8, the total energy consumption of ring machines during manufacturing was calculated as 3950.5 kWh with the present approach. If the total consumption is divided by production amount, the specific consumption is obtained as 1.32 kWh/kg and this value seems to be 3% lower than that obtained by the equation (10). The difference between these two values is attributed to the difference detected in parameters such as speed, waste ratio, mechanical efficiency, and energy loss of ring spinning machines.
As a result of detailed investigations into energy consumption for yarn manufacturing with special reference to ring spinning, important findings are summarised below.
- It was shown that the manufacturing machines consume 72% of the total monthly energy consumption (1459680 kWh/month) while air conditioning comprises 16% of the total energy consumption in the chosen spinning mill. Additionally, specific energy consumed for each month in a one-year period was calculated and it was determined that the calculated values change between 3.23 and 3.76 kWh/kg.
- With the simple model developed, the total energy consumed during the manufacturing of 100% cotton, 20 tex combed ring spun yarn in the chosen spinning mill, was calculated as 9961.7 kWh, 71.3% of which was consumed by manufacturing machines. The highest energy consumption with 55.5% share occurred in spinning machines alone. The values calculated were compared with the data available in the literature and it was shown that there was a close agreement between calculated data and data given in the literature. The small differences were attributed to differences in operation parameters such as type, mechanical efficiency, energy loss and the waste ratio of machines.
- The specific energy consumption for 20 tex combed ring yarn was obtained as 3.32 kWh/kg and this value was compared with the values outlined by ITMF (changing between 3.49 and 3.62 kWh/kg for the same yarn type). The difference between calculated and reported values are thought to be because of the difference in production parameters.
- The specific energy consumption of the ring spinning machine during the chosen yarn production was calculated as 1.32 kWh/kg by the given approach, while this value was obtained as 1.36 kWh/kg by the equation given in the literature. There seemed to be 3% percentage difference between the calculated value and data taken from literature.
- It has been demonstrated that the approach given in this study can be used to calculate the total and specific energy consumption of a particular type yarn with reasonable confidence.