So, WREC starts tomorrow, so I've been preparing my presentation over the last week. As I've been doing the living below the line challenge I've not been the most happy and smiley person this week, the lack of food has made me slightly more grumpy than normal (many would say this is a great feat as I'm fairly grumpy most of the time anyway!) and so the pressure to get a good and coherent presentation together hasn't helped the situation. However, after a couple of iterations during the week and a practise on Friday I'm quite happy with what I have. I'm going to be giving my presentation in the first hydropower session of the conference on Thursday morning, which means I'll have most of the week to see how everyone else does theirs and see what the style and level of the presentations are. I've also been thinking about the awkward questions that I'm likely to be asked so that I can have useful responses to them. The questions I think most likely are:
- Why don't people normally use these turbines at low head as they're not new technology?
- How big will the turbine be?
- What is the advantage of this compared with the axial flow turbine (the normal turbine used at low head pico ranges)?
- What about using pumps as turbines?
I've also learnt a bit more about what you need to do in a conference to present your work. You don't necessarily need to give all the data that's in the paper, in fact you can give more data than the paper and any new information that you've learnt. I thought I'd be able to only present what I'd initially written and so focussed my presentation on that, however I've been told that people aren't that interested in that, more what you're doing now and what you're going to be doing. Let's see how it goes…
As well as preparing for the conference I've been doing some further testing on the turbine. I've a new nozzle - 20mm diameter jet, which produced a fantastic 85% efficiency on the turbine. I have to say I breathed a sigh of relief. I was beginning to get concerned that my turbine choice I had made was fundamentally wrong. So the good efficiency measure is great news. Now we have to go forward with a organised testing regime, covering all the possible variables in the design - jet velocity (head, flow rate), jet inclination angle, jet impact location and so on - and see what affects the efficiency most, finding the optimum location. I'm still struggling with matching my model to the results - when I reached 85% the model was fairly close, within a reasonable error, but when the turbine moves away from this optimum point then this consistency with the model drops away dramatically.
So, to combat some of the problems with the model, I've been looking at further improvements, trying to implement some sort of 3D flow in the cup, as I've seen in the experiments that it is certainly not two dimensional flow. To see this yourself, if you put a spoon under a tap, as pictured below, you can see that the flow goes in all directions. This also happens in the turbine. However, form initial runs of this model, it doesn't seem to solve the problem, so I think I may have to come up with a completely new strategy. More frustration definitely!
Spoon and turgo cup under a 'jet' from a tap - see how the flow goes pretty much everywhere!
I've also been looking at some of the electrical building blocks I'll need to use in my system. Firstly the phase locked loop controller, that is used to synchronise two AC signals together. Once this was done, then I used it to control two independent voltage sources to parallel them up - replicating two generators connected together. I've managed to synchronise two units together - as you can see on the graph below:
Trying to synchronise two AC generators
Two problems have appeared though. The time to synchronise is quite long, about half a second, which is not really acceptable. There is also a 100Hz ripple in the frequency, as you can see the line is not at a constant frequency. This would not cause a big problem, but is annoying. I've tried filtering this out, but this causes a slow reaction in the control of the sources. So, these are a couple of problems to overcome.
I've bought my tickets to return to Nepal in July, which I'm really looking forward to. It's been almost a year since I was there last, and I can't wait to see all my friends again and just relax back into the wonderful culture and lifestyle that the Nepali's have. I met up with Tim Mitchell, a member of the Rotary club (Rotary Club) who does a lot of work with the Pahar Trust. The Pahar Trust are an NGO that build schools and medical posts in rural Nepal. They are also interested in electrifying them, and so after the IMechE presentation in March he came to talk to me about using the technology we're looking at to provide power to their schools. This is quite exciting as it could provide the possibility of test sites at the end of the project. So, I'm going to try and meet up with the Project Manager of the Pahar Trust when I'm out in Nepal, and maybe visit some of their projects.
I went home for Easter, as it had been a long time since I had been back to Cornwall. It was great to see my parents again, and Mary came down from up north for a few days, so all the family were together, quite a rare occasion. Hannah and I also decided to take a few days off on May Day bank holiday weekend, as we weren't that keen on watching THE wedding. So we booked a cottage just outside Abergavenny and plotted a weekend of walking, cycling (my choices) and shopping (Hannah's choice). We went to Brecon and found the Nepali shop there - I wanted to buy something, so bought some chiura and muri. Not very exciting, but still necessary. We went walking around the black mountains and climbed Sugar Loaf, which was blowing a gale on the top.
Climbing up sugar loaf
Near our house was Llanthony Priory which was destroyed in the dissolution of the monasteries in the mid 16th century. It was a very beautiful place to sit and relax, and quite interesting as I'd been reading some books about the dissolution period of British History.
Llanthony Priory
We cycled up the valley we were staying in up to the pass. Doing this we climbed over 300m, which almost killed both of us - I think I definitely need to improve on my fitness. But we had a really good picnic at the top of the pass, and then freewheeled most of the way back down the valley in 45 minutes, when it took us almost 3 hours to cycle up it!
The road to the pass - very very very tiring to reach it, so much quicker to go back down!
On the final day we went for a cycle on the Brecon Monmouth canal, much easier to cycle along and a nice relaxing time. We didn't want to expend too much energy though as we were starting to live below the line at that point, so we wouldn't be able to replace any lost calories with excesses of chocolate, as normal.
So, now I'm just about to head off to Sweden for my first conference. I'm nervous as anything, but looking forward to it too. Sort of!
SAM
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