What design of a drive system should I use?

[Ballena Joseph]

Hi there! I am currently making a design about drive systems used for micro-hydro scheme. I don't know what type of driving element is suitable to used for transmitting the power from a turbine (cross flow turbine) to a generator. I'm planning to use both chain and sprocket & V-Belt Pulley which are mounted on the Line Shaft. The reason why I include the line shaft is because I think it will increase the speed of the turbine through the generator that also makes the power to increase. I don't know if my thoughts are correct in making the design. Please, help and give me some advice. Thank you!

 

[CWatters]

Just a heads up.. you cannot increase power by changing gearing. If you increase rpm you decrease torque.

The exception to this is if increasing or changing the rpm somehow improves the end to end efficiency of the system. Perhaps by allowing both turbine an generator to operate at their max efficiency rpm (which might be different).

 

[CWatters]

Not sure why you plan to use both a chain and belt drive? Why not two chains or two belts? Perhaps Google the efficiency of different transmission systems. The efficiency is a measure of the power wasted due to friction etc.

 

[Ballena Joseph]

Not sure why you plan to use both a chain and belt drive? Why not two chains or two belts? Perhaps Google the efficiency of different transmission systems. The efficiency is a measure of the power wasted due to friction etc.

I also think of that before. But our professor requires to make a design with 4 or more elements. So I decided to use both chain and belt drives together with line shaft and bearings.

 

[Ballena Joseph]

What if I use two belt drives, do the power from turbine increases by transmitting it through the line shaft to the generator?

 

[anorlunda]

What if I use two belt drives, do the power from turbine increases by transmitting it through the line shaft to the generator?

No. It sounds like you missed a very important lesson about the conservation of energy.

We can't give a good answer without some basic info.

1. What kind of generator?
2. How much power?
3. Turbine RPM
4. Generator RPM

 

[Ballena Joseph]

No. It sounds like you missed a very important lesson about the conservation of energy.

We can't give a good answer without some basic info.

1. What kind of generator?
2. How much power?
3. Turbine RPM
4. Generator RPM

Base on my computations:
1. ?
2. 2.72 kW (turbine)
3. 762.26 rpm
4. ?
1 and 4 are still unknown, unless if I will base them on the typical specification of generator for micro hydro schemes.

 

[CWatters]

One function of the drive train is to match the rpm of the turbine to the required rpm of the generator. So you need to know both before you can design it.

 

[Ballena Joseph]

One function of the drive train is to match the rpm of the turbine to the required rpm of the generator. So you need to know both before you can design it.

So, does it mean I need, first, to select the specification of the generator?

 

[CWatters]

Yes.

 

[Ballena Joseph]

Yes.

Okay. So, is it okay if I use a line shaft and a set of two v-belt pulleys? One is connected to the turbine and the other is connected to the generator.

 

[CWatters]

If your supervisor wants multiple elements I guess that's ok. Remember belts also need tensioning.

 

[Ballena Joseph]

If your supervisor wants multiple elements I guess that's ok. Remember belts also need tensioning.

What do you mean by tensioning? What if I use both chain and belt drives, is that okay?

 

[CWatters]

Belt drives rely on friction between the belt and pulley. If the belt is slack it just slips on the pulley so it has to be tensioned.

Before doing a lot of work on the drive system I suggest you look at your other thread and decide if the idea is feasible. For a possible extra mark from your supervisor look up heat recovery from grey/waste water.

 

[Ballena Joseph]

Belt drives rely on friction between the belt and pulley. If the belt is slack it just slips on the pulley so it has to be tensioned.

Before doing a lot of work on the drive system I suggest you look at your other thread and decide if the idea is feasible. For a possible extra mark from your supervisor look up heat recovery from grey/waste water.

What do you mean by heat recovery from waste water?

 

[CWatters]

What do you mean by heat recovery from waste water?

Quite a lot of the water used in a hotel is hot water (eg showers). Hotels need a large heating boiler to provide all that hot water. After showering all that hot water and the energy it contains is thrown away. Google greywater heat recovery.

 

[CWatters]

It wouldn't be too hard to estimate how much energy is being thrown away in hot waste water. Perhaps assume fresh water arrives at the hotel at around 15C and half of the water consumed ends up going down the drain at say 35C after someone used it to shower with. How much energy is potentially available in the waste water? How does that compare with it's gravitational potential energy?

 

[Ballena Joseph]

It wouldn't be too hard to estimate how much energy is being thrown away in hot waste water. Perhaps assume fresh water arrives at the hotel at around 15C and half of the water consumed ends up going down the drain at say 35C after someone used it to shower with. How much energy is potentially available in the waste water? How does that compare with it's gravitational potential energy?

I don't know what to do now. I want to know how much energy does a hot waste water have. I don't even know if that energy would produce much power.

 

[CWatters]

Ok first think is to decide if the microhydro approach is feasible. If not then speak to your supervisor about another project.

It is possible to extract heat from waste water but i think it would be quite difficult for you to build such a system. I think you need a heat pumps to do it and building a heat pump is quite a complex project for a student.

 

[CWatters]

To calculate the energy in the hot water look up the specific heat capacity of water. That tells you how many joules of energy you need to raise 1 gram of water by 1 degree centigrade.

 

[Ballena Joseph]

Ok first think is to decide if the microhydro approach is feasible. If not then speak to your supervisor about another project.

It is possible to extract heat from waste water but i think it would be quite difficult for you to build such a system. I think you need a heat pumps to do it and building a heat pump is quite a complex project for a student.

I don't think that adding a heat pump is a good idea. At first, we need to design a

To calculate the energy in the hot water look up the specific heat capacity of water. That tells you how many joules of energy you need to raise 1 gram of water by 1 degree centigrade.

I'm sorry for my bad attitude on my another thread. I'm just panicking. I can't think of right now. I'm really sorry.

 

[Ballena Joseph]

To calculate the energy in the hot water look up the specific heat capacity of water. That tells you how many joules of energy you need to raise 1 gram of water by 1 degree centigrade.

What if I assume the value of power and head as well as the volume flow rate to the specification of cross flow turbine? In order to proceed through the computation of my drive system?

 

[CWatters]

Yes if this is just an exercise in designing a transmission, then you could use the data for a turbine designed for a small river/stream.

 

[russ_watters]

What if I assume the value of power and head as well as the volume flow rate to the specification of cross flow turbine? In order to proceed through the computation of my drive system?

Doing the proper design process of first identifying the available energy is neither difficult nor time consuming. I don't understand why you don't just do it. Is it explicitly not part of the assignment? I think if I were grading a design project where someone designed a truck when a bicycle would have worked fine, I wouldn't give it a good grade, even if it was a well designed truck. Typically the main point of such projects wasn't the design, it was showing you can approach the design like an engineer.

Your focus on the transmission system is oddly specific and out of order...or even irrelevant. Is there something relevant about the assignment's requirements you aren't telling us?

 

[CWatters]

Russ..

I believe this is related to this thread where we did the calculations for available power and energy..

https://www.physicsforums.com/threads/suitable-net-head-for-a-hotel-wastewater.956503/

 

[Ballena Joseph]

Yes if this is just an exercise in designing a transmission, then you could use the data for a turbine designed for a small river/stream.

Really?

Okay. So, am I be able to proceed on the transmission of power?

 

[CWatters]

Really?

I think you need to speak to your supervisor. Tell him/her that the power available from hotel waste water is too low/not feasible.

Ask him/her if you can design a for something else. Something like a turbine suitable for a small river.

 

[Sherwood Botsford]

Base on my computations:
1. ?
2. 2.72 kW (turbine)
3. 762.26 rpm
4. ?
1 and 4 are still unknown, unless if I will base them on the typical specification of generator for micro hydro schemes.

800 rpm seems VERY slow for a small turbine. And 2.72 kW is indeed small. I saw a pic of a 1 kW natural gas turbine that spun at 100,000 rpm and was about the size of your fist.

Also: 5 place accuracy on your RPM? Really? Do you need speed control to that accuracy?

 

[CWatters]

800 rpm seems VERY slow for a small turbine. And 2.72 kW is indeed small. I saw a pic of a 1 kW natural gas turbine that spun at 100,000 rpm and was about the size of your fist.

Also: 5 place accuracy on your RPM? Really? Do you need speed control to that accuracy?

You need to see the other thread. I believe these figures are in error.