In order to obtain the specifc energy consumption of any yarn, each an every machine in the spinning operations right from the bale opener and the approach should be repeated for the rest of the machine/step.

## The Approach

In order to obtain the specifc energy consumption of any yarn, a simple approach was developed. Since a manufacturing line contains many steps/machines, the approach is explained here for the frst machine which is outlined as the bale opener and the approach should be repeated for the rest of the machine/step.

According to this approach, raw material used for each machine should be frst found and then the operating time of each machine obtained. Using the operating time and actual power of manufacturing machines, the energy consumption of each machine during manufacturing could easily be calculated.

## Formulas to determine energy consumption

The amount of raw material R1 (kg) which will be processed in the frst machine (bale opener) can be found by using the total waste ratio WTot (%) and mass of the specifc yarn, M (kg) as

Operating time for the frst machine, t_{1} (hour), can be determined as follows,

where; L_{1} (kg/h) is the manufacturing rate of the machine, n_{1} is the number of machines used and N_{1} (%) is the mechanical effciency of this machine. With given parameters, the electrical energy, E_{1} (kWh), used for the frst machine can be obtained by

Here, N_{1} (kW) is the installed power of the frst machine N_{E1} (%) is the energy effciency concerned. After calculating the energy consumption of each step, the total energy consumed for operating the machines, E_{M} (kWh), can easily be calculated by the following equation.

where E_{i} is the energy consumption of blow room (E_{1}; energy for bale opener, E_{2}; energy for cleaner, E_{3}; energy for mixer etc.), E_{Ca} is the energy consumption of carding, E_{D} is the energy consumption of drawing, E_{Co} is the energy consumption of combing, E_{R} is the energy consumption of roving, E_{S} is the energy consumption of spinning, E_{W} is the energy consumption of winding step, i represents the relevant individual machine and n is the total number of machines in the blow room.

Energy consumption of compressors for the frst machine, E_{A1} is found as

where C_{1} (m3/h) is the compressed air needed per hour, N_{A} (kWh/m3) is the unit power for compressors which can be determined by dividing the installed power of the compressor by the compressed air capacity. Total energy consumption for providing compressed air in general,

and here again j represents the relevant machine and m is the total number of machines that need compressed air in the production line of specifc yarn.

Energy used for air conditioning during yarn production E_{C} is

where, E’_{C} expresses the total energy consumption of the air conditioning system in one month while G is the monthly yarn production in kg. Similarly, the energy consumption for illumination, E_{il} (kWh) is found as

Here; E’il is the total monthly energy usage of lamps needed for illumination.

Consequently; the total energy consumption for any specifc yarn can be calculated by summing up the relevant energy consumption equations given above as

## Prediction of Energy Consumption

The energy consumption for 20 tex (Ne 30) combed ring yarn produced in the spinning mill under investigation was calculated by applying the procedure given above. Here; 3000 kg, 20 tex combed yarn is supposed to be produced in the ring spinning system at a speed of 17500 rev/min and with a twist factor (atex) of 3828.