Flat plate heat exchangers and flushing.

[Captain Echidna Senior Member Find all posts View Profile Close Captain Echidna]

I am nearing completion on my landcruiser (80 series 1HD-T) conversion.
I am wondering if it is better to put the flatplate heat exchanger (FPHE) either just before the injection pump, or before the changeover solenoid (in this case the relocated one from between the 2 tanks) I have another heat exchanger to put before the filters.

If I put it before the IP, the oil will be very hot before the engine, the solenoid will have cool(ish) oil going through it, the IP will have been pre-heated on diesel.

The question I have is though, will the heat exchanger flush out well when I shut down, or will it still have lots of veg oil in it in its cavities? I am having flashbacks to my gemini which shared a fuel filter for both diesel and veg, and it would not flush between changes, which made starting near impossible.

If I put the FPHE before the changeover solenoid, the engine will run on either cool diesel ot heated veg oil. When I start however there will be a time when cold oil is going into the IP (which was sitting in the hose), folowed by very hot oil (that was sitting in the FPHE) and hot oil will be going through the solenoid. Will this be a problem?

Your thoughts please?

[Fitian Was here Find all posts View Profile Close Fitian]

Re: Flat plate heat exchangers and flushing.

Hi Chris,

After finishing my 300D conversion using ... 20 FPHE > CAV filter > Pollak valve > lift pump then engine. I then found out that I take too long to change over so I bought this twin coil HE and placed it after the Pollak valve. Now I change over in less time and my fuel(S) are going hot vegy or warm BD too to the engine. Cold start is not a drama since I start on BD. and it gets warmer in the twin coil.

Good luck mate.

Fitian

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Flat plate heat exchangers and flushing.

Chris,
It all depends on where i nthe fuel system you locate the FPHE.
Please post a diagram of your configuration so that I can give an informed reply.
Tony

[Captain Echidna Senior Member Find all posts View Profile Close Captain Echidna]

Re: Flat plate heat exchangers and flushing.

I did the first of the options, where it goes, 1 heat exch> filter >flat plate heat exch> changeover solenoid> injection pump, unfortunatley this means the IP does not get heating before the veg oil goes in.

And incedentally the FPHE gets the oil to between 60 and 75 degrees C.

Perhaps the seccond diagram would be better, but how well will the diesel wash out the heat exchanger?

The engine is now leaking lots of fuel oil from the injector pump, on the engine side. Sounds like "1HZ with some issues" post.

[Alga Senior Member Find all posts View Profile Close Alga]

Re: Flat plate heat exchangers and flushing.

I've been looking everywhere for a flat plate heat exchanger, can someone tell me where to get them ni Aus. All I can find is a couple of barrel ones.

[Sunnysideup Junior Member Find all posts View Profile Close Sunnysideup]

Re: Flat plate heat exchangers and flushing.

Hi Chris,

My suggestion is not to run diesel through the heat exchanger at all, therefore place the HE before the solenoid. I notice you have a return line to veggie tank - there are pros and cons of having this - the cons are the loss of heat and more work for the fuel pump - and the pro is the clearing of air from the line.

I came across the following set up that I am going to integrate into my system because it will allow for quicker, more thorough and more accurate purging of the lines.

Diesel tank - diesel fuel filter - supply valve Normally Open (NO)
WVO tank - WVO fuel filter - FPHE - supply valve Normally Closed (NC)

Supply valve Common (COM) - LP/IP - Return Valve Common (COM)

Return valve NO - to diesel tank
Return Valve NC - to tee in WVO line before WVO fuel filter

This system means that you would require 2 solenoids - one for the feeder line and one to distribute to return fuel. - When purging you are temporarily sending diesel back down the veggie feeder line - and as each fuel has its own filter purging is greatly sped up -

I just came across this system in my searchings on a variety of forums - I was concerned about my present system continually contaminating the diesel tank with veggie whenever I switch back to diesel - this system will eliminate this.

I hope this gives you a few more ideas.

Jason

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Flat plate heat exchangers and flushing.

I will be listing them again on eBay in mid January. They are listing at around $100 +/- and sell for up to $150 each. I would be happy to supply you one if you wish to contact me by PM.
Tony

[Guest Close David]

Re: Flat plate heat exchangers and flushing.

Flat Plate heat exchangers can be bought from Mashmaster.
Their 20 Plate exchanger page can be found here.
They are selling for $99. I think I saw somewhere that delivery is $10 but I can't find it now to confirm.

I was talking to a friend yesterday who works with heats exchangers on an industrial scale and is very familiar with the Flate plate kind. I was telling him about some of the reports about these exchangers not heating the fuel sufficently and my thoughts that the exchangers should be plumbed in series with the heater not in parralell.

I explained the application for use in vehicles and showed him how they would be set up on my vehicle.
His thoughts were that the only way these exchangers could NOT heat the flow of oil from a 5/16 line when they were supplied with hot coolant from a 5/8" line to the same temp as the coolant temprature was if there was insufficent coolant flow such as when the exchanger was tapped off a "T" with the heater rather than the coolant being forced through it in a series configuration.

He said that although there were things to be taken into consideration like the heat absorbtion value of the oil being lower than that of water, Even on a small flate plate unit, their efficency is so high that the slower flow of the oil coming from a much smaller supply line as against the coolant flow rate, would more than make up for any of these differences.

He also believed that the amount of heat that would be removed from the coolant if it were passed through the FPHE and then to the heater core would be irrelevant in all but the coldest of climates because of the amount of heat that is available and the efficency of the heater core. As he pointed out, the only time you use the heater full blast is for a short time till the car warms up and then it is only used at a fraction of its capacity.

If people are having trouble getting their fuel up to temp and are using a FPHE, I would suggest they try plumbing the HE in series before the heater and see if there is any difference. If the fuel is not hot enough, check the thermostat in the car is operating correctly and what the setting on the thermostat actually is. As far as I am aware the coldest thermo is 79oC and I have seen thermos that are rated at 92oC which are interchangeable.

It would probably be correct to say check what temp thermo is reccomended for your vehicle but experience says as long as the car does not overheat, you can't put too hot a thermo in as the car would exceed the temp of the hottest thermo within it's normal operating temps anyway.
It is also worth bearing in mind that on most engines the coolant flow to the heater core comes straight from the engine and is unregulated in that it comes from the engine hot and is then passed through the heater and returned to be regulated by the thermostat. The thermostat can only regulate the minimum temp of the engine not the upper temp so the coolant coming from the engine can be any temp at all above the thermo rating.

Once the vehicle is warmed up, a FPHE with proper coolant flow should have no problems warming the oil to the desired temps and above.

[Captain Echidna Senior Member Find all posts View Profile Close Captain Echidna]

Re: Flat plate heat exchangers and flushing.

With the hear exhangers and wether to go series or paralell depends on if the heater has a tap in the system. Some heaters (gemini for instance) pass coolant contstantly through the heater core. In summer, the air is bypassed around the heater core. In this instance then putting it in series would be the correct way to plumb it.

With a car with a heater tap (landcruisers and mercedes W123's) if it is put in series, and the tap is turned off to stop coolant going through the heater, then coolant will not flow through the heat exchanger.

I guess ideal would be a system that does series when coolant flows, and paralell when it doesn't. (yes this would be complex)I did see a ford replacement heater tap in a shop which had 4 connections, but I have no idea why.

[Guest Close David]

Re: Flat plate heat exchangers and flushing.

Chris,
You are correct about some cars having the coolant going through the heater core constantly and just diverting the air either around or through the core for heating.

I believe that many systems, such as those found on late model commodores and Merc W123's ( among others) use the heater tap to divert the coolant flow rather than to stop it all together. In other words, the coolant dose not pass through the heater but is still circulated through the heater circuit. Both the commodores and the W123's have 4 port heater taps for what I believe is this reason.

I would suggest this is to stop pockets of water that were not circulating in the head or block ( wherever it is tapped) from becoming overheated and causeing steam pockets and uneven cooling of the engine.
I am quite sure that this would be the situation with the W123 as the coolant is tapped from the back of the head and if this port was blocked, coolant flow would be very limited if any at all.

As such, I believe tapping into the heater circuit near where it originates from the engine would still have a constant flow in most vehicles although if memory serves correct, some older cars ( although I'm thinking of Petrol Vehicles) did have a simple on/off tap.

This being the case, a person would do well to follow your suggestion and check out the coolant flow path and plumb their heat exchanger accordingly so it recieves a constant and substantial coolant flow.

Because the heater control on my W123 is frozen in the on position and any air blown by the vents is hot, I would like to find a 3 port valve even if it were manual so I could turn the heat off. I figure a 3 port valve would be a good option till I can get hold of a functioning original heater control at a more realistic price than what I have been quoted so far

[Captain Echidna Senior Member Find all posts View Profile Close Captain Echidna]

Re: Flat plate heat exchangers and flushing.

The W123 has 3 ports, one for each side of the car and one for the coolant to go into (or out of I cant remember)

I have been quoted $115 or thereabouts through MB spares in canberra for a heater tap. Nice to know I am not the only person who's heater is stuck on. Could this have something to do with the conversions we have done and the tap not having enough flow to turn off properly?

I thought the flow that is required all the time (get rid of air and to allow some coolant flow) would not have gone near the heater, or relied on it. My guess would be if it does,if it does then it would not be enough to heat the heater much, therefore also the heat exhanger.

I do like the idea of using an alternate coolant path other than the heater, so I will investigate this.

[Guest Close David]

Re: Flat plate heat exchangers and flushing.

Nice to know I am not the only person who's heater is stuck on. Could this have something to do with the conversions we have done and the tap not having enough flow to turn off properly?

At present my engine and cooling system is completely stock so I would suggest the heater tap problem is probably more to do with the fact we are driving cars that are closer to their 30th birthday than they are their 10th!
I wonder why they stick on and not off?

I got a similar price for a heater tap which to me is a lot for what the thing is. I might go out and have a look at just bypassing the heater for the time being with a bit of copper pipe and connecting it back up again when the weather cools off.

[Alga Senior Member Find all posts View Profile Close Alga]

Re: Flat plate heat exchangers and flushing.

Thanks to everyone for the info on the FPHE, its been an enlightening thread and I look forward to putting all the ideas into action very soon

[Fitian Was here Find all posts View Profile Close Fitian]

Re: Flat plate heat exchangers and flushing.

To put my mind at ease, I went ahead and changed my set up.

Before,

I had a T in the middle between the engine and the heater going to the HE. and it goes to another T to the other side of the engine.

Now,

I put back the other side of the engine to origianal way. and fitted the FPHE and the twin coil HE in series.

I took the car for a drive and noticed that the FPHE got hotter faster even though the weather is cool.

I will post more update next year if you can wait.


Happy New year everyone

Fitian

[Alga Senior Member Find all posts View Profile Close Alga]

Re: Flat plate heat exchangers and flushing.

Is their any reason you are using both flat plate and twin coil heaters Fitian and which one have to got first from the tank.