Tuesday, August 21st, 2018

Exergy and economic analysis of a pyramid-shaped solar water purification system: Active and passive cases

Publication year: 2012brbSource:/b Energy, Available online 23 January 2012brAli Kianifar, Saeed Zeinali Heris, Omid MahianbrAn exergy analysis has been conducted to show the effect of a small fan on the exergy efficiency in a pyramid-shaped solar still. The tests were carried out in Mashhad (36° 36′ N), for two solar still systems. One of them was equipped with a small fan (active system), to enhance the evaporation rate while the other one was tested in passive condition (no fan). To examine the effects of radiation and water depth on exergy efficiency, experiments in two seasons and two different depths of water in the solar still basin were performed. The results show that during summer, active unit has higher exergy efficiency than passive one while in winter there is no considerable difference between the exergy efficiency of the units. Results also reveal that the exergy efficiency is higher when the water depth in the basin is lower. Finally, the economic analysis shows a considerable reduction in production cost of the water (8–9%) when the active system is used.brh3 class=h3Highlights/h3► Using a small fan in the solar still; reduces the productive cost of fresh water up to 9%. ► Effects of the fan and basin depth on the exergy efficiency during summer and winter were examined. ► Utilizing an active system will increase the daily productivity of fresh water by 20%.


Responses to “Exergy and economic analysis of a pyramid-shaped solar water purification system: Active and passive cases”
  1. Yunita says:

    Jeffery, you’re certainly right that the more coplmex end of solar heating systems won’t be viable for most of the deindustrial dark age ahead of us. Mind you, the ancient Greeks made a lot of use of passive solar heating — there are simpler ways to do the thing, if you don’t mind results that aren’t up to current expectations — and that, along with earth-sheltered housing (another ancient practice that works very well), are likely to be going concerns even in the harshest part of the near-to-middle future.Tyler, good heavens. I don’t ignore nuclear power; I’ve discussed several times the likelihood that it’s going to be the next ethanol — that is, the recipient of a huge amount of government largesse, resulting in an equally huge number of economically nonviable nuclear plants, many of them half-finished, cluttering up the landscape. (I’ve even put one of those into a recent chapter of my online novel . You’re quite right, also, that the future inhabitants of this and several other continents will be dealing with radioactive dead zones. I haven’t discussed it in detail because it hasn’t been relevant to the themes I’m trying to develop just now, but of course it’s an issue. Sofistek, that’s an excellent point. I doubt it will be given the attention it deserves by anybody, but it’s still an excellent point. Kyle, good. As far as I know, there isn’t a single good source for data of the sort we’re discussing here; like everyone else in the peak oil field, I’ve assembled the estimates I use bit by bit from a wide variety of sources, many of which are doubtless skewed one way or another, and the weighting I give them is inevitably also skewed by subjective factors. Basically, we’re all guessing. Still, I don’t know of any PV systems actually in production that have proven, in practice, to have a 2-3 year payback time — 20-30 years seems to be much closer to the way things work out — and the energy subsidy issue there is immense. You’re right that there’s a lot of room for efficiency, and also for demand destruction that doesn’t actually impact critical systems; as I’ve pointed out more than once, the entire tourist industry could be scrapped, with an immense savings in energy and resources, and the only people who’d be harmed are the ones who lost tourism-dependent jobs (which are going away anyway). This is one of the reasons I argue for a long descent instead of a fast crash; even with relatively rapid rates of oil production decline, there’s a lot of waste that can be trimmed to make up for it, at least for a while. Xhmko, good. The middleman analogy is an excellent one; every transformation of energy is a middleman who takes his cut — often a sizable one. Dan, if you glance back over last week’s comments you’ll see that DIYer made the comment about photons I was referencing. I used it precisely because it demonstrated a very common mistake in thinking about renewables, one I’ve seen repeated countless times. Of course I’m simplifying the issue of exergy, but I don’t think what I’m doing with it is that unclear. If you’d like to suggest an alternative term for “the amount of useful work that can be done by a given amount of energy in a given concentration, under broadly specified environmental conditions” I’d welcome that. For the 19th and early 20th century solar energy projects, the book to read is A Golden Thread by Ken Butti and John Perlin. That’s my source for the info on Shuman and Mouchot, including the brandy! LS, excellent. Yes, wind is the one stellar exception to most of the problems with renewables; it has problems of its own, but its net energy is respectable if not stellar, and it’s likely to be an important piece of any functional response to our predicament.

  2. Chad says:

    Ok. I was planinga small syestm for a guy who wanted to power a couple of 15 watt lights a small tv set for a couple of hours a night. Not knowing how much power your fish tanks will require, I will give you what he is looking at doing.60 watt solar module 388.37Trojan 80AH AGM battery 187.95Sungaurd-4 4.5 amp charge controller 30.00Pro-watt 400 watt inverter 63.36Cost before shipping and taxes 669.68 USDHe will be using a long cord and mount the solar module out side and put the charge controller, AGM battery and inverter inside. Simple setup that he wants because he can take it with him when he moves. has enough powe to get you through the night. The battery will hold 960 watts of power just using half 480 watts would let you power 120 watts of items for 4 hours and keep the battery above half charge.If you were to use that much power with a 60 watt solar module as the only source of power It would take 8 to 10 hours of peak sun light to recharge the battery. That should give you some kind of an idea of what you would need a an idea of the cost. Hooking it all up is pretty simple, Hook the Plus on the modules to the Solar Plus on the charge controller. Then hook the Battery Plus on the charge controller to the Plus on the battery. Same for the inverter. Plus to plus and Neg to neg.You might want to ask a few more questions or read up on things a little before you do it .. But really it is all pretty simple. Remember that it is electricity and can burn or kill a person. Be careful.

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