Off grid solar indirect/direct evaporative cooling.

Projects General Guidance
1

Hello,

I would like to briefly outline my project and hopefully receive some feedback.

We are in a position of living in a very beautiful location in Australia. We have constructed a dwelling from 2 20ft containers set 6 metres apart with a full roof over and a raised floor in between.

The front and rear( north and south facing ) walls consist of aluminium bifold doors extending the full width and height of the opening between the containers, giving us the opportunity to fully open up the living area.

We have an 'Off grid' solar power supply soon to be supplemented with wind turbine power.

Our climate is such that temperatures of the seasons is "extreme" enough to warrant some sort of climate control.

For winter we have a combustion stove which provides heating to the living area alone.

For the summer I have researched evaporative cooling and settled on a design ( as mentioned in the topic title ) and will begin fabrication once I have the whole project on paper.
Fortunately I have a brother in law who is a hvac consultant to help in that part of the design.

My main objectives are;

1: Achieveability ( within the scope of my existing skills and abilities and also within my ability to learn new skills with perhaps some tutoring )

2: Cost effectiveness ( I already have most of the components and materials )

3: Self gratification ( Sounds strange I know, but isn't that why we are attracted to Arduino and the like )

The cooling unit will be operating at 24v supplied by a PV system of 3-200w panels giving 600W charging approximately 1000 amp hour of batteries to operate fans, pumps and electronics.

From this I can convert down to 12v 10A and further if necessary.

I envisage the ability to interface with available technology ( Iphone ) remotely for setup, fault monitoring and diagnosis.

At present I am looking at the Arduino Mega with wifi shield and using 'Arduino manager'.

List of some control hardware I have;

2-"battleswitches" from Dimension Engineering
( BattleSwitch Radio Controlled 10A Relay Switch )

1- RS160D PMDC servo controller from Robot Solutions
( http://robot-solutions.com/RS3/index.php?route=product/product&manufacturer_id=11product_id=51 )

Various servos from an old futaba to a HITEC HS-755HB ( HITEC RCD USA )

Many other components new and salvagable from other electronic devices and projects.

I realise there will be other components to be purchased but I think the whole project would be in the reach of everday people wanting to 'scratchbuild' an affordable climate control system capable of being enviromentally sustainable.

Looking forward to your opinions

Thanks
Peter

2

I made a simple evap. cooler for my backyard orchid greenhouse(6'×8'). During the summer, it keeps the temperatures under 95 F when it's 115 F in Southern California desert. It works well for dry climates. It's a very thirsty system, unfortunately, and water is a rare commodity here. I feel a little guilty, but it seems like there is another water main bursting in L.A. every other day so I'm not the worst offender. I have played around with the idea of going solar but I can't afford it at the moment. someday maybe.

3

Hi seanz2003,

The evap cooler I'm looking at is the hybrid indirect and direct type.

First stage the supply air is drawn/pushed through 'channels', sort of like in a car radiator but in reverse.
Water outside air inside.

The air is kept separate from the cooling water sprayed onto the cores with forced air driven by fans to complete the evaporation process.

It then flows to the direct 'swamp cooler', just like a standard evap cooler, which can further cool the air and add humidity if necessary.

The water will be recycled but loss is expected.

As for the solar it is our only option as the cost of putting mains power on is prohibitive, exorbitant and downright robbery.

The cost of solar is now at an affordable level, mostly thanks to our friends in China, and very easy to setup.
Batteries being the largest outlay, but hey, I'm just using truck batteries ATM and they are holding up ok(touch wood!!).

This obviates the need for some sort of control, besides me having to manually turn on fans, pumps, dampers, water control etc.

The arduino appears to be the choice for a DIY'er like myself.

Having seen numerous youtube videos and websites I think smart phone control is a practical and logical progression.

Yes I will need to learn a new skill in writing code, but you never stop learning do you.

With the automation and the design of the cooler I hope to be as economical as possible.( and also green)

Only too willing to share my results with the wider community.

Peter

4

Your description of the project is very interesting but you have not made any attempt to describe exactly what you want the Arduino to do.

I suggest you leave the communication part of it to last and concentrate on getting a functioning control system working with data displayed in the Arduino Serial Monitor. When it works, the communication is simply a case of sending some value or receiving another value

You may get some useful ideas from planning and implementing a program. You should also look at the examples that come with the Arduino IDE - they cover a lot of common usages.

...R

5

You are almost describing my property Peter, central QLD, two 20-foot containers with a breezeway that can be closed off, slow combustion stove, solar system.

Do you have enough water to drive this? We don't unfortunately.

It seems that the Battleswitch is designed to be driven from an RC receiver, if so it's not a very good choice for general control.

The link to the PMDC servo controller is broken, but again it seems like an RC product and as such I don't see it being appropriate for this, unless I missed something.

There are many solid state relays (SSRs) that take a logic signal directly.

Rob

6

Hi Robin2,

Thanks for your reply.

I guess by posting in this forum I was seeking some guidance as to what could be done, within the scope of a project such as this.

Automation is the first thing to come to mind followed by interfacing with available smart phone technology.

As previously mentioned, the starting point with regard to Arduino was the selection of a suitable platform such as the Mega and connectivity via a wifi shield.

As to managing that connectivity the Arduino manager app appears to fit the bill.

Do you think this would be a suitable combination?

As for sensors there are a number of options from a LM35 to a DHT22, of which I would be seeking advice for. Notwithstanding the various abilities of said sensors.

Output looks as though it would be to the devices that I mentioned I already have plus perhaps some solenoid valves for water control or alternative methods for same.

Again advice on the suitability of various components is also sought.

Unfortunately I am not at present able to commence fabrication and installation of the unit due to a quad bike accident which has left me a little disabled at the moment.

I return to hospital tomorrow for further operations to remedy the injury and depending on the level of my pain relief some of my posts might be a little garbled.(If they aren't already)

My apologies in advance.

This is where I thought that attacking this side of the project at this time would be relevant given my condition.

Your advice is welcomed and I will follow up on your suggestions as far as logistics (SWMBO and doctors) let me.

I look forward to your thoughts

Thanks
Peter

7

Hi Graynomad,

The water consumption should be minimal due to recycling within the system.

The indirect system basically sprays the water onto the 'cores' to which the air flows through. A fan is then applied to create an airflow to enhance evaporation. As the water flows down the 'cores' to a sump it is then recirculated to the sprays. Water level is maintained by a float valve. Flow direction of the air, be it counter flow or cross flow, would be a determining factor in water consumption.

The greatest loss would be through the direct evaporation section. (just like those cheapy mobile evap coolers).

The most important thing to consider is the relative humidity of your location, less than 50% is preferable.

With refridgerated air conditioning as the temperature rises efficiency is diminished.

With Evaporative cooling the opposite happens, as temperature rises the efficiency increases although dependent on humidity.

Hope that helps you a bit there, the pain relief is starting to kick in.(As mentioned in my reply to Robin2)

I take note of your mentioning the suitability of those switches and controller and will investigate further.

I have seen the ssr's I think you are referring to and they are reasonably priced but if I can use what I have that would be good.

Thanks
Peter

8

Graynomad,

Yes I see the problem with the link. If you go to their website, http://robot-solutions.com, and look for DC servo controllers it is listed as an obsolete item. I tried to copy and paste the address but it won't work.

Peter

9

Here's the link

http://robot-solutions.com/RS3/index.php?route=product/product&path=59_60&product_id=51

But as I said don't see that all this RC stuff is appropriate for general purpose control like this.

We live in a very dry area so this would be good for us, OTOH we don't consider that it gets very hot here (mid 30s normally in summer, occasional high 30s) so it's not required.

Rob

10

Oldergeek:
Automation is the first thing to come to mind followed by interfacing with available smart phone technology.

Many people starting with an Arduino tend to think of the whole project as a unit. That is usually a recipe for late nights, headaches, too much coffee and eventual disillusionment.

It is much more practical to think of any project as a series of small interconnected parts each of which can be developed and tested separately before combining them into the bigger project.

So. for example, write a short program to read the values from your LM35. And do the same for the other things you are going to connect to the Arduino. That is the approach in the planning a program link that I gave you.

...R

11

At first sight, it doesn't seem especially complex - an Uno might well be sufficient.

Basically, you need to read the temperature and if it's too hot, turn on the cooler. In addition, you want to turn the system off if it's too humid, sump shows no water or (I assume) battery voltage is low. Does the arduino have to manage the charging system(s) too?

You may want to vary the temp and humidity thresholds on the fly. You likely want a display of some kind to show you thresholds and current values, even if that's just the serial monitor.

I'd get that going as a standalone controller before you add in the arduino manager piece.

Is the iPhone piece so that you can control the system from the couch or from Christchurch?

Do you have wired ethernet in your home? If so, is there any reason that the arduino has to be wifi? Wifi shields are more expensive than ethernet.

12

Good morning,

Just a quick reply before I head off to the hospital.

Rob,

I will look further at alternatives to those components.

We are in the new far North of the New England region and the worst thing is the warm/hot still nights.
With SWMBO working shifts this can be problematic. I suppose it depends on your comfort levels.

I will be working on some cad drawings for the system to be put up once design is finalised.

...R,

Yes, I can see what you mean after having a brief look at your tutorial.
I have ordered a UNO and a MEGA for later on( appears to be better suited to the manager app).
When they arrive I will study your tutorial in depth and I think painting by numbers is a good way for me to start learning a new skill.

Wildbill,

The charging system is stand alone system controlled by a solar PV MPPT controller.
24v is preferred to power the fans and using 24v to 12v automotive transformer for the other other components.

I suppose the ideal system controller would maintain a preset temperature e.g. 26 degrees C.
This is well enough in summer but transitioning to heating in winter would be desirable. This would be achieved by controlling dampers in the air return ducts to distribute the warm air.

As the supply of power is not an issue the system could run the fans(as long as they would last) etc. 24/7.

With regards to the Iphone control it would only be from within the confines of the house itself.
I had considered being able to turn the system on remotely via phone to cool/warm the house before getting home for example, but as power consumption is a non issue as the HVAC system power supply is separate from the main house supply.

I think wireless control would make installation a lot easier, especially in retrofit situations, and it is something we all have become used to thanks to the TV remote. Of course an 'emergency' manual control overide would also make sense.

Hope I'm not rambling too much, while these pain killers are not my drug of choice( to quote Homer, mmmm beer) they help somewhat.

Thanks to all for your input.

Peter

13

I would be very interested in seeing a sketch of your cooler system. Sounds interesting. I integrated my cooler into a complete greenhouse controller ran by an UNO. The controller monitors temperature, humidity, air circulation and venting. It has an LCD display for showing current conditions and a web interface for directly turning on fans, valves, and vents. If your setup is within range of your wireless router or access point then a wifi shield would be fine. Ethernet is also an option as is bluetooth if you don't have or need internet access. As far as controlling your devices (fans, pumps, and valves), MosFETs are probably the way to go for a DC system.

14

Hi Sean,

By 'sketch' I'm assuming you mean a drawing and not Arduino code ( haven't got that far yet).

I will try to do some drawings in paint and upload them here.( when the head clears a bit more, got home from hospital late last night.)

P.s. love the balloons.

Hey WildBill,

Not sure if I misunderstood your reference to ethernet connection, but I have seen some ethernet shields connected to a modem/router to interface with Iphone. Got to do a price/performance comparison with wifi shield. One thing to keep in mind is the house is totally constructed from steel being containers, corrugated iron roof sheeting for the ceiling, steel trusses and steel roofing iron.
Not sure how this will affect wifi communications but it's one hell of a Faraday cage.

Rob,

Still not sure the RC components will not work, seen internet examples of Arduino interfacing with them.
Certainly appreciate your experience, what do you think the issues with them could be?

Again Thanks to all

Peter

15

Sean,

Best I can do with paint, Autocad is my preferred weapon of choice(love that Fatboy Slim video with Christopher Walken).

Red arrows = outside ambient air

Green arrows = water flow

Blue arrows = cooled air

Peter

sketch.JPG
sketch.JPG1321×710 50.1 KB

16

I'm just suggesting that if your phone can already talk to your router, it would be able (with configuration on the router) to get to any other device on your home network, wired or wireless.

Of course, if you want the arduino to be in a location where running ethernet cables to it would be a pain, perhaps the (slight) extra cost of a wifi shield would be worthwhile.

17

Hey Wildbill,

I guess the location of the Arduino would ideally be as close as practical to the what it needs to control,
without undue electrical interference.( mounted in a waterproof enclosure on an external wall?)

Locating a modem/router with or nearby would be practical depending on signal quality to the controlling Iphone e.g. through the steel structure.

I think these issues would apply both to ethernet/modem or wifi shield.

The determining factors would be which would work better, cost and ease of setup.

Thanks Wildbill.

18

The Faraday cage issue you mention sounds as though it may be a serious consideration. Do you have internet connectivity and/or a LAN in your nuclear shelter home?

19

Wildbill,

I'm not sure, but I know the missile silo and machine gun nests do!!!!!

Seriously, we get a couple of bars on the Iphones but this depends if you are standing on one leg(very nearly came to that with the quad bike accident) with your thumb up your(I won't say it).

I suppose I could always extend an antenna or ethernet cable into the house.

Peter

P.s. the Mega arrived today so I can start to look at learning how to use it.

20

I came across this today in relation to the 'Battleswitch'

and the video