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SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Wood stove thermal heat creation and storage

I have talked about using a wood stove to supply heat to sand or water that is in a storage location that is already common to other such heating sources from other means, making a hybrid system.

DIY Wood Stove Water Heater Plans

We Built a DIY Woodstove Hot Water System for Indoor Wood-Heated Water

In the words of Void Not Done!!!!

I am being interrupted by the family...

tahanson43206

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Registered: 2018-04-27

Posts: 19,383

Re: Wood stove thermal heat creation and storage

This post is reserved for an index for what I hope will be a number of supportive posts by NewMars members.

While a wood fired thermal energy storage and heat pump hybrid system may exist somewhere on Earth, I doubt it.

NewMars is where such an ambitious project might develop from idea to full fledged working system.

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

Now that I have lost my train of thought for what was to get posted here is an image.

Here is the typical coil of tubing around teh flue.

Then again, a wood burning furnace comes to mind

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

Sending the heat from any working fluid can also be done in this manner as well

Experimental study of a ground-coupled heat pump combined with thermal solar collectors

tahanson43206

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Registered: 2018-04-27

Posts: 19,383

Re: Wood stove thermal heat creation and storage

For SpaceNut re #4

This is the Wood stove topic....

Where is the wood stove in the image you are showing us?

The solar panel is a nice addition to the project, but the heart of the system is the wood stove.

If you doubt that, please go back and read the opening post by the topic manager for this topic.

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

Substitute the wood stove in the location of the solar collector and gas water heater and the same system remains for storage of the heat produced by burning wood.

Here is a decorative unit.

Heres what a poor man's radiator might look like

Then again is all you want is to heat the air in the home you would capture the heat going up the flue

So, it's not just about the wood stove but a means to generate heat energy for later use directly or indirectly depending on when you are in need of it.

here is what the storage trough cug with the pipe but not the sand might appear.

One needs to have the loops with sand in between the coils to maximize the heat.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

What quantity of wood is needed to support a family for a year?

I am able to collect fallen limbs from my trees over the course of a year. In a typical year, the quantity of wood shed by the trees would make a decent wheelbarrow load, or small fire that would last for an hour or so.  If you are contemplating heating and cooling a home with wood, you will need railroad carloads of wood, over the course of a year.

Whether in pellets or cord wood you end up with 3-4 tons of pellets or the same number in cords of wood. for winter heating.

Thats why this is a backup to creating thermal stores when the weather is not sunny. Then again so would rain or streams for waterpower to electrical and then to heat elements in the sand and that is how wind would also work as well.

That said understanding heating in general is required whether by any fuel form in use.
What Is a Furnace Heat Exchanger and Why Is It Important?

Its where we get into heat exchanging and how to plumb the heat into storage.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

Related topics with content for the storage aspect as well as some creation for the hybrid system.
http://newmars.com/forums/viewtopic.php?id=2919
http://newmars.com/forums/viewtopic.php?id=10035
http://newmars.com/forums/viewtopic.php?id=10510
http://newmars.com/forums/viewtopic.php?id=10258
http://newmars.com/forums/viewtopic.php?id=10388

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,383

Re: Wood stove thermal heat creation and storage

For SpaceNut about topic ....

In the olden days, it was possible for a home owner (or even a renter) to imagine burning wood to heat a home or to provide for hot water and cooking. 

In some parts of the world, it is no longer socially acceptable to pour clouds of black soot into the air.

Your design for a thermal storage and heat pump system needs to include industrial scale cleaning of the exhaust from a wood burning combustion chamber. Only CO2 and N2 can be permitted to escape into the atmosphere. All other particles of matter, and any nitrous Oxide in the effluent must be captured and stored for safe disposal. The same would certainly be true on Mars, with even more strick regulation.

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

My thoughts are to plumb the exhaust into the ground and filter through a water or amine solution so that after giving up its heat to the sand that it exits cleaner than it entered.

other suggestions
These simple tips will help you reduce your wood-burning stove’s environmental footprint [with video]

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

For your consideration:

[8' x 8' x 2' = 128 cubic feet = 4.74 cubic yards

1 cubic yard of dry sand weighs 2619 pounds. So you are talking about 12,416 pounds of sand. (4.74 x 2619 = 12,414)

The specific heat of sand is 830.

The specific heat of water is 4182.

So a pound of sand will hold about 20 percent what a pound of water will hold. (830/4182 = .198 = 19.8%)

A btu is defined as the amount of energy required to raise 1 pound of water 1 degree Fahrenheit. This tells us that to store one btu of heat, you would need to raise 5 pounds of sand by 1 degree Fahrenheit.

So, for each degree that you raise your 12,414 pounds of sand, you will be storing 2483 btus. (12,414/5 = 2483)

A single gallon of propane contains 91,500 btus. So, you would need to raise the temperature of your box of sand by 36 degrees to store the equivalent heat energy contained in a gallon of propane.

https://www.calculator.net/btu-calculator.html

Here is the electrical to heat Heater Room Size Calculator: What Size Room a Heater Heat?

Seems that a 1,500 BTU Heater Room Size: 50 sq. ft. or 1,500 Watt Heater Room Size: 150 sq. ft. by changing the units in the calculator.

so, at 40kwhr /24 hrs = 1 2/3 kw for 800 sq ft. with a heat pump 30,000 to 36,000 BTU = 3 ton heat pump to heat my home.

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,383

Re: Wood stove thermal heat creation and storage

For SpaceNut ...

Thank you for the link to the article on reducing emissions from wood burning, in Post #10

And thanks for the quote showing actual numbers for sand thermal energy storage.  The 20% of water figure quoted was a surprise to me, but Calliban has been warning us for months/?years about poor performance of stone for heat conductivity.

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

Yes, rules of thumbs will get you close.

Heating BTU Calculator: How Many BTUs Per Square Foot?

Question: How many BTUs do I need to heat 1500 sq ft? How many square feet will 30,000 BTU heat?

Example: To heat 1500 sq ft home, you will need anywhere between 45,000 BTU and 90,000 BTU.

Zones 1 & 2 (hot): 30-35 Btu/sq. ft.
Zone 3 (warm): 35-40 Btu/sq. ft.
Zone 4 (moderate): 45 Btu/sq. ft.
Zone 5 (cool): 50 Btu/sq. ft.
Zone 6 (cold): 55 Btu/sq. ft.
Zone 7 (very cold): 60 Btu/sq. ft.

Being that I am in zone 6 I get to use even more due to the moisture and cold of the area.

First step if you can afford the materials to upgrade you home.

The sun helps too but you need to be clear of trees.

“Very Sunny” means something very different in Denver (245 days with sun) than it does in Portland, Oregon (142 days with sun), even if there are no shade trees around the house. Therefore, consider the map below.

My climate is more like Portland being in NH.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

Improving wood products could be a key to reducing greenhouse gas emissions, researchers suggest

https://dx.doi.org/10.1186/s13021-024-00254-4

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Wood stove thermal heat creation and storage

Recovering electricity from heat storage hits 44% efficiency

The research team reports that their new device has a power conversion efficiency of 44% at 1,435°C, within the target range for existing high-temperature energy storage (1,200°C-1,600°C). It surpasses the 37% achieved by previous designs within this range of temperatures.

In a heat battery, thermophotovoltaics would surround a block of heated material at a temperature of at least 1,000°C. It might reach that temperature by passing electricity from a wind or solar farm through a resistor or by absorbing excess heat from solar thermal energy or steel, glass or concrete production.

The heated storage material radiates thermal photons with a range of energies. At 1,435°C, about 20-30% of those have enough energy to generate electricity in the team's thermophotovoltaic cells. The key to this study was optimizing the semiconductor material, which captures the photons, to broaden its preferred photon energies while aligning with the dominant energies produced by the heat source.

A recent study found stacking two air bridges improves the design, increasing both the range of photons converted to electricity and the useful temperature range for heat batteries.

"We're not yet at the efficiency limit of this technology. I am confident that we will get higher than 44% and be pushing 50% in the not-too-distant future," said Forrest, who also is the Paul G. Goebel Professor of Engineering and professor of electrical engineering and computer science, materials science and engineering, and physics.

https://pubs.acs.org/doi/10.1021/acsenergylett.4c00774

https://dx.doi.org/10.1016/j.joule.2024.05.002