On 5/9/2016 at 9:45 AM, DeepBass9 said:

I have been building a hot water circulation system onto my generators cooling system to circulate the hot cooling water through radiators in the house for winter heating. On cold cloudy days I run the generator for power, and a by product of the power is 150l of hot water in the coolant tank. Apparently for an engine about 1/3 goes to power generation, 1/3 goes to heating coolant and 1/3 goes out of the exhaust as heat.

I am using a fridge thermostat to control the system which drives a geyser circulation pump. 

Once the coolant temp reaches 45 degrees, the pump switches on and runs until the water drops below 35 degrees. Yesterday I ran the generator for 3 hours, the coolant reached a maximum temp of 63 degrees and the hot water circulated in the radiators for another 3 hours after the generator was switched off. The generator produces about 2Kw at the inverter, so maybe 3kW at the crank so the engine was producing 9kWh over the period. 150l of water raised by about 40 degrees gives about 7kWh of water heating (1.16wh to heat one liter of water by one degree centigrade). So I have therefore almost doubled the energy efficiency by capturing the waste heat. The next step I suppose would be to try and capture some of the exhaust heat. 

New radiators cost at least R7k each, and I couldn't find any second hand ones, so I built them out of copper pipe.

The first is a bit of a sculpture, using the form of a labyrinth, and the second a bit more conventional. I still need to finish the building and then apply some brasso, but you get the idea. 

Love it. Make a plan

This is fantastic. 

J

On 09/05/2016 at 9:23 PM, Clint said:

Awesome skills there DeepBass9

I want to purchase some copper pipe in the next week to see if I can make a camping water heating system. I've already purchased the !2V shower pump.

The copper pipe I want to use is the pipe they use in gas installations 

I saw the other day that Western Gas in Kdorp West stocks soft copper pipe in various diameters if you want to try this.

Just plotted my power generation/consumption for April. Consumption is on the way up for some reason. Maybe getting lazy about switching things off!

May energy use/production. Solar efficiency on its way down due to the fixed array angles (the 1200W array actually points a few degrees south), and less usage. Some of the solar production has also been replaced by using the generator for heating.

On 2016-6-14 at 6:52 AM, DeepBass9 said:

Happy anniversary to me! 1 year off grid! 

2 years now, Trojans still holding up. Probably getting close to payback on the investment by now....

3 years off grid now. Trojans still fine, one set will be on about 1100 cycles and the other on 900 now. DOD usually around 70%.

That's great. How's the radiator heating pannels working now that is getting chilly. Have you looked at rocket mass heaters for heating ?

The radiators work great, I usually start the generator at 5am when I get up, so that everyone can use the toaster, microwave etc, I put it off at about 7am. I wouldn't say that it heats the room, but it takes the chill off the place. I also have a secret electric heater under my desk that I put on when the genny is running to keep my toes warm in my office. 

I think the cost of a bit of diesel in winter to keep the batteries well charged is cheap in comparison with a new battery bank.

Edited June 11, 20188 yr by DeepBass9

4 hours ago, DeepBass9 said:

DOD usually around 70%.

DoD, not SoC? I can't find a cycle life for the T1275, but at least one other forum says you can expect 700-800 cycles at 80% DoD. If they are T105 good, then 1200 cycles at 50%, and if T105-RE good, then 1600 cycles at 50%. So you are doing exceptionally well then!

Ja, SOC rather.

According to the data sheet I have, 30% DOD gives you 2000 cycles, 50% DOD = 1200 cycles. When I bought them they were about R2500 each, so I think I am getting very good value out of them.

Edited June 11, 20188 yr by DeepBass9

Hi DB9, have you tried running Waste Veggie oil in youir Roid yet?  Lots going on in that department on listerengine forum right now.

I have using old chip oil, filtered and mixed with some diesel. I don't have a supply of used oil though and I don't make chips that often! Which lister forum is that?

This one 

http://www.listerengine.com

 

 

To continue this story, I have now bought some bits of pipe and fittings to built an exhaust heat exchanger to heat water in the winter when the generator is running. The exhaust is currently a 40mm steel  pipe,. I have a 1m long 80mm galvanised pipe and some fittings so I will test my welding skills to the limit to built this. I can usually convince two pieces of metal to stick together, but this will need to be a watertight weld. Unless I stick it with pratley steel?

So the plan is to have a circulation pump that runs when the generator runs which will circulate the water through the heat exchanger and solar geyser. It is a low pressure geyser so any boiling water will just squirt out the top, but if that happens then the system is way exceeding expectations.

I should then have a close to 100% efficient heat engine, 1/3 of the energy goes to electricity generation, 1/3 goes to house heating via the cooling water, and as much as I can catch in the heat exchanger goes to hot water heating.

Edited April 5, 20197 yr by DeepBass9

56 minutes ago, DeepBass9 said:

I have a 1m long 80mm galvanised pipe

The heat transfer to the water over only one meter will be insufficient. I used to calculate air/water heat exchangers. There is commercial heat exchangers available but they are expensive. Maybe you can use an old car radiator and make a funnel type of shroud and connect the exhaust pipe to the outside of the radiator and run the water through the radiator.   

After a few minutes of the engine running, the exhaust is hotter than 100 degrees, and its thick pipe, like 4mm so there is a lot a heat to be captured. The 40mm pipe will run through the inside of the 80mm pipe. For supplemental water heating in winter I only need to raise the water temp about 30 degrees. This is also an old style diesel engine so it can run for many hours doing its thing. Currently that heat is going to waste, or compounding global warming perhaps. So by my logic if you have 1m of hot metal, surely by encasing that in a water jacket, you can use that as water heating.

Edited April 5, 20197 yr by DeepBass9

56 minutes ago, DeepBass9 said:

After a few minutes of the engine running, the exhaust is hotter than 100 degrees,

Years ago in one of the bakery's I worked in, i had to come up with a plan to heat water. We had a 400 liter hot well feeding the boiler and to make the boiler more efficient you need to heat up the inlet water to save on  fuel cost. the hotter the inlet water the less fuel is used in the boiler to heat up the water. I decided to coil copper pipe around the steel chimney of the boiler and wrap the lot with asbestos tape. I had a temp sensor, controller, solenoid valve, blow off valve and circulation pump in the circuit. I allowed the water to circulate till the water in the hotwell was 95 degree c . it never reached that because  the boiler used more water that what i could heat up, but I could maintain the water in the hotwell at above 70 degree c. 

I believe the same can be applied in your application.  The more coils, the more heat transfer. The picture below will give you some idea of what I am trying to say. In the bakery it was a much bigger installation, but this should give you some idea. 

If you coil copper pipe around a longer area of the exhaust, you might get better heating than the 1 meter of pipe. Also consider wrapping everything to reduce to heat loss to atmosphere in this hole process. 

 

I have considered that, but that copper tube is not cheap and the bits and pieces I have didn't cost very much. I'll see how it works, but complete immersion in water should work better? Experimentation will reveal the answer.

Look at aluminium tube they use it in aircon piping in place of copper , it's easier to bend and form , cheaper too . Not sure on the fittings if they will join up to the plumbing stuff. Wrap it up in a 50mm ceramic wool blanket and it should work a treat.

On 2019/04/05 at 7:17 PM, Jaco de Jongh said:

you might get better heating than the 1 meter of pipe.

I now suddenly remember something from my third year applied maths class, a difficult subject called fluid dynamics that I passed with 54% and bid farewell forever after that. Tensor math just wasn't my thing... however, I remember one thing about how water flows through a pipe. It sticks to the sides of the pipe, and it flows slowest there, but in the middle of the pipe it flows fastest. It essentially creates radial layers of laminar flow with the fastest liquid in the middle, so you can visualize it as a bullet-shape. So the water on the outer layers moves the slowest and absorbs the most heat, while the water in the middle essentially flows right past and absorbs no heat at all.

So what that would mean is you want the pipe to be a smaller diameter, and you want to maximize the surface area. So I agree with Jaco here, that might work better.

12 minutes ago, plonkster said:

I now suddenly remember something from my third year applied maths class, a difficult subject called fluid dynamics that I passed with 54% and bid farewell forever after that. Tensor math just wasn't my thing... however, I remember one thing about how water flows through a pipe. It sticks to the sides of the pipe, and it flows slowest there, but in the middle of the pipe it flows fastest. It essentially creates radial layers of laminar flow with the fastest liquid in the middle, so you can visualize it as a bullet-shape. So the water on the outer layers moves the slowest and absorbs the most heat, while the water in the middle essentially flows right past and absorbs no heat at all.

This is true. Over-stretching a stainless steel spring ( or equivalent) and inserting it into the length of the pipe will create turbulent flow.

OK, I'll see what I can find to break up the flow. I don't think the water will flow very quickly through the exchanger though as the circulation pump has 20mm connections and once you expand the pipe to 80mm you will lose a lot of velocity.

4 minutes ago, DeepBass9 said:

OK, I'll see what I can find to break up the flow

the heat transfer from the exhaust pipe to the water will more than sufficient without modifying the flow characteristic. The problem is the heat transfer from the exhaust gas to the pipe. 

I'll build it maybe next weekend, and then measure how long it takes to boil a known volume of water, then I'll see whether it is worthwhile plumbing it into the geyser. Otherwise I'll pop a teabag inside and use it as a tea urn.