Energy consumption is different on various yarn types, for example energy consumption for combed yarn is higher because of the additional production step - combing.

## 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 fner 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). Specifc 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 specifc energy consumption in a ring spinning machine, ER (kWh/kg), can be calculated with the equation given below

where; F is the linear density of yarn (tex), Dr is the diameter of ring (m), n is the speed of spindle (1000 r.p.m.) and atext 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., atext = 3828 (ae = 4) and Dr = 0.04 m. If these parameters are evaluated in the equation (10), the specifc 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 specifc 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 effciency and energy loss of ring spinning machines.

## Summary

As a result of detailed investigations into energy consumption for yarn manufacturing with special reference to ring spinning, important fndings are summarised below.

1. It was shown that the manufacturing machines consume 72% of the total monthly energy consumption (1459680 kWh/month) while air con ditioning comprises 16% of the total energy consumption in the chosen spinning mill. Additionally, specifc energy consumed for each month in a one-year period was calculated and it was determined that the calcu lated values change between 3.23 and 3.76 kWh/kg.
2. 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 ma chines. The highest energy consump tion 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 literature. The small differences were attributed to differ ences in operation parameters such as type, mechanical effciency, energy loss and waste ratio of machines.
3. The specifc 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 is thought to be because of the difference in produc tion parameters.
4. The specifc energy consumption of the ring spinning machine during the chosen yarn production, was calcu lated as 1.32 kWh/kg by the given approach, while this value was ob tained as 1.36 kWh/kg by the equation given in literature. There seemed to be 3% percentage difference between the calculated value and data taken from literature.
5. It has been demonstrated that the app roach given in this study can be used to calculate the total and specifc en ergy consumption of a particular type yarn with reasonable confdence.