Richard goes crunchy:

There is a shop in Charing Cross station, which I used to refuse to go in (except once whilst drunk) which sells all kinds of organic/fair-trade/horrendously worthy, dried fruit. I refused to go in partly because of the apparent possibility of catching hippy and partly because when the shop first opened one of the promoters offered me some form of luminous coloured shrivelled sample saying it was “mother nature’s candy” (Shudder).

Well it appears I may have caught hippy (maybe one drunken exposure is enough) because the current hobby project is the construction of a solar drier for fruit.

Nigeria is blessed with an inordinate number of Mango trees, each producing about 1000 fruits. We are now approaching mango season where there are more mangoes around than it is possible for the Nigerian populous to eat. A UN report (I know, I have far too much spare time) recons around 50% of the mango crop is wasted . A suspiciously unscientific and round percentage if you ask me, but we’ll use until I can be bothered to further investigate mango production in Nigeria which will probably be never. If only there was some way to store them, so mango could be enjoyed all year round..... enter project dryer.

The basic design of an indirect dryer can be seen above. Air enters at the bottom of a thermal collector (1), heats up and rises through the main drying chamber (2), passing the stuff whot you want to dry (3) and taking with it some water. The ideal drying temperature is around 50°C any higher and you end up with cooked product any lower and bacteria etc can still multiply. Nigeiria’s air temperature at the moment is around 38-40°C so a temperature rise of 10 degrees should be fairly easy (but the design might have to be adaptable through the year).

I am also trying to build a really low cost direct solar dryer with Hope For The Village Child (HVC) but these have the drawback that the direct sunlight breaks down all the vitamins and discolours the end product. The type sold in the shop in Charing Cross will be indirect dried, with some form of preservative treatment before drying to preserve the lovely bright colours.

So what i needed was a small metal box for the drier with a big thin, flat, metal box to act as the collector. As everyone knows there is only one place to go in Kaduna for such a construction... Pantaka (insert sudden intake of breath, or something like “not Pantaka that’s suicide” etc).

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Pantaka is Kaduna’s post apocalyptic industrial area where all kinds of woodwork and metalwork are carried out. The place is cross between the middle ages and a Mad Max film, pots of molten aluminium bubble away on the side of the dirt tracks which crisscross each other away from the tarmac road where HGV’s, vans and okadas bring in raw materials and take out “finished” goods. The atmosphere is rancid, the background music is the constant hum of generators but if you want get some scrap wood, need some spot wielding or fancy seeing some of the worst examples of child labour and poor health and safety in the world (I hope), this is the place.

Aluminium smelters casting a cooking pot, note the careful use of safety flip flops.

The whole place is organised in sections with an area for each trade and then subareas for each specialism, it took us a while to locate the metal section, then find the sheet steel section. We found a nice man called Bash (yep that is his real name, “hello i’m Bash the metal worker”) and suppressing inner giggles I judged somewhat inexpertly that he seemed to have the requisite skills to construct a glorified metal box.

Clutching my carefully prepared bit of paper with diagrams on, we began the difficult task of explaining i wanted one metal box than wouldn’t fit in the other and wasn’t a piece of furniture. After a lot of explaining and re-explaining to the surrounding crowd of workers in Hausa, a chorus of generally satisfied “Na garne” (i understand) was muttered by all. In this process I carefully demonstrated on the diagram all the dimensions, and even tried to build a model out of scap bits of metal lying around the place. I though that they had grasped the idea.

Two days later I returned and was presented by drier box twice the size shown on the diagram, with a tray in the bottom. Some re-explaining happened, more money changed hands, as the single sheet of steel we purchased would no longer be enough, and there was much more Na garne.

Eventually on the third visit and under supervision for the last couple of bits/hours (“what is he doing”, “cutting the second hole”, “errr, i don’t want another hole”, “ah”) we finished the dryer.

The guy who made almost the entire dryer using only a hammer, a sharp bit of metal (for cutting), a steel girder (as an anvil) and a hell of a lot of ingenuity.

This is the project come to fruition*, set up at Moniques Deaf School (they now have a large collection of my solar based nonsense projects).

Luckily it can also be used for meat the most capitalist and manly of snacks so I can cancel the tie dye T-shirt order and have a shave.

Making the wire racks to go inside. These are normal steel so we’re putting a layer of thin fabric (new handkerchiefs) down first so they don’t rust onto the fruit.

Today we started drying pineapple, which is about the one dried fruit product which i’ve actually tasted, further updates will be posted once this is actually dry(or not if it doesn’t work) .

* I had to use this pun once

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The obvious question is why, and how much did all this cost. The total cost of the metal sheets and labour was N9,000 (£36), racks were N750 (£3) and if i have to paint it this will be around another N500 (£2). This is about twice what i think will be an “economic” price, assuming the ability to dry around 3kg of fruit in two days. This version only has 3 racks over the one meter and has to be loaded from the top, I think in any new version it needs to have 6 racks across half the size and have a hinged back to allow easy loading.

All I need now are some customers. The plan is to start drying the product and using it to illustrate what is possible, as yet no Nigerian i have met belives that the crazy box will work, not even my amazing side kick the deaf school driver Malam lawal, hopefully this will change soon!

As ever i apologies for the length of the post, and the delay in posting since last time. I hope everyone is good back at home, and i enjoy reading your comments and I might actually respond to some if I knew the answers.

Geeky Addendum

I don’t let the inner physics geek out very often in public but here goes:

If you’re feeling geeky the total area of metal exposed to the sun is a 1m² (0.5*1 for the collector and the box itself), Solar radiation has a peak power of around 800wm^-2 and the energy required to evaporate water is 2260kjkg^-1. Some simple maths later shows that it will take four hours to evaporate a kilo of water if the whole process is 25% efficient, the limiting factor i think will be airflow around the fruit.

From an extensive literature review (hahaha) there will be two stages to the drying, the first evaporation limited and then a second stage where the limiting factor will be the transport of water from inside the fruit to the edges where it can be removed. (they’ll also be some boundary layer effects, but i unless anyone has a PhD in fluid dynamics i think we’ll just leave it with, this will slow the process down somewhat.

In terms of the evaporation and and humidity limitations, I have stolen the following graph from Wikipedia:

As you can see at 35°C water can hold 38g of water per m² (also assuming density of air to be 1kgm^-2 as I am very lazy and this isn’t the most rigorous of analysis). If you heat the air to 50°C the holding capacity rises to 95g. The total volume of the Mk I is 0.5m² meaning to evaporate 1 kg of water will need the air to change around 10 times, but probably closer to 30 if you assume a 30% efficiency. If i had some form of flow meter i could work out how quickly the air is changing inside the box from the flow at the top, but i dont so we'll all have to wonder what could have been if i had brought one with me.

What this graph does show conveniently is that even if the air is saturated at 35°C, you can still use a dryer effectively if the temperature is increased by 15°C.

Also you can see that at the current difference between night and day temperatures (23°C night, 38°C day) the humidity would have to pass RH50% for dew to become a significant problem, as its around 10% at the moment fruit can be left overnight with minimal worry.

Accountancy at the sharp and pointy end

As many (all?) of you know in a former life of pork products and all day electricity I was an accountant, the letters which now expensively grace the end of my name apparently designate some form of sharable skill. In the hope of spreading the simple word of double entry, rates of return and income statements I have been working with a NGO called Hope for the Village Child on their microfinance program.

This first involved me desperately reading everything the internet could tell me about microfinance, which told me many things. The first was that I have never actually been an accountant, secondly that this didn’t matter and thirdly and most worryingly that deep down i quite like the bits of this accountancy malarkey which are like financial engineering (I can definitely recommend- Measuring Microcredit Delinquency: Ratios Can Be Harmful To Your Health, 20 pages of pure geeky fun).

After thoroughly reading up on the subject I had a couple meetings with the two people who would be administering the microfinance program. This obviously changed everything, and the plan in my mind went from “microfinance empire” (poorly received) to “I think you’ll need to use what is known as a spreadsheet “ (Enthusiastically received) this may be the only time someone else was more enthusiastic about excel than me. Getting ahead of yourself is a bit of an occupational hazard here, remembering to start small and work from there is the name of the game.

Every January they disburse hand out agricultural loans of around £20-25 to groups of women to help in the improvement of their farms. Each group consists of five or six woman and the whole group is joint and severally liable for the loan of the whole group. Most of these loans should be put to buying goats/renting farmland/developing new income streams. To put it in perspective, £20-25 is probably more than rural families live on a month.Previously these groups have used the money to simply buy up food just after the harvest and then re-selling once prices have risen, which isn't quite the life affirming, liberating change HVC is looking for.

Designing how to do this effectively surprisingly never came up on the ICAS Audit exam.

You have a group of Illiterate woman, who speak only the local village language and a bit of Hausa, a shopping bag full of money, One Land Rover, 2 pens and some paper. What controls would you put in place (12 marks).

The first day we went out we were dealing with around 50 women, and the whole thing nearly descended into a riot. With people pressing in a crowd around the Land Rover (my new mobile office) hands, paper and money everywhere and people giving any old name their group leader told them to give

Example conversation:
Mercy: "whats your name?"
Woman A "err.."
Woman B "Aggie Bobbins"
Woman A" yes how silly of me to forget Aggie Bobbins is the name, chimney sweepings the game"
Mercy "how do you spell that"
Woman A "err...."

In video form

There are a number of problems with the above:

• Explaining that this money is a loan and has to be repaid
• Figuring out who you are dealing with
• Making sure that who you give the money to actually gets to keep it.
• Getting them to spend it on something worthwhile with the money.

Most of this is work in progress... ideas on a postcard please. We had problems with men hanging around and I suspect simply taking the cash off the woman as soon as we had headed back over the horizon.

Money is in the jargon term fungible. Advanced microfinance theory states trying to control what the money is spent on is pointless and all that is needed is to provide the cash in the family unit will efficiently allocate the capital. In theory, theory is the same as practice, in practice its not. Nigeria has the habit of taking advanced theories down unlit backstreets and beating three kinds of hell out of them and stealing their wallet. However once you give someone some money its quite difficult to get them to spend it on what you want them to spend it on so even though I (plus HVC staff) don't like the theory we're pretty much stuck.

Mercy (who runs the woman’s program and can be seen in the photos) said “we’ll probably come back to find them all with new wrappers”.It’s nice to not be the cynical one all the time!

The simple solution to the identity problem was to take photos of each participant:

This amused the hell out of the customers, “who is this crazy white man with his crazy camera and tiney tiny whiteboard”. But hopefully this should impress on people that “we know who you are” and that the are entering some form of enduring system, its almost all a deterrent factor but hopefully we’ll see higher repayment rates. The rest of the changes will be around general microfinance theory awareness and the record keeping (almost accountancy).

Look at their happy smiling faces

These loans are one year(ish) in duration and attract 10% interest. Which is both a long time and a pretty soft loan (the interest doesn’t cover inflation), so hopefully we’ll be working towards some more text book microfinance over the next six months or so. Currently the farmers whole business model does revolve a single planting season, normally of a single or two crops with a single harvest. This is fine for a western farmer who has access to insurance markets, subsidies, irrigation,fertilisers and a welfare system. For people who have access to none of this it doesn’t take a genius to spot this is somewhat of a high risk strategy.

HVC works on grain banks, to give the farmers a way of storing some excess. Over the next couple of weeks I’ll be using my dubious physics skills to work on building some food dryers. Proper and hygienic drying should allow people to store the early rainy season fruit for up to year and selling this fruit should be an easy way to raise cash (especially if done on a community level, leading to smaller transport costs, more division of labour etc.) The dryers are as simple as a polythene tent over a table, with sliced fruit laid out on wire racks (but don’t tell anyone they think it’s my in-depth knowledge of physics that allows me to copy the design of the internet). I’ll post some photos once they’ve actually been built.

My tragic tale i won’t prolong, you’ve only yourselves to blame if it’s too long, you should never have let me begin....

Rich vs the Rat

Mr ratty has been thwarted, by everyone’s favourite stuff... beer. Now he can’t get under the kitchen door I haven’t seen him for a week (cancel the harpoon order Jon).

Before

After

Result: Score Draw - no kills on either side.

There is another hole in the bathroom which lets water from the shower/bucket out. I can keep the door shut but this isn't a long term solution. I fear me and Mr Ratty have not ended our struggle for mutual destruction.

Hope everyone is well, I have a proper blog entry coming soon!