Two important characteristics of water:
1. As water freezes into ice, it expands in volume by approximately 9.4 percent.
2. For every atmosphere of pressure applied to water, the effect is its freezing point lowers by approximately 1/100th of a degree Fahrenheit.
In order to produce energy from this method there needs to be a way to:
A: Allow the transfer of heat from the atmosphere into a chemical catalyst. (Water)
B: Convert the slow moving force from the expanding/contracting volume of the chemical catalyst into a faster moving force so that electrical energy can be produced.
To accomplish A, a device called a heat exchanger is used. This is similar to a car radiator that uses air to cool the chemical inside carrying the engines heat through a zig-zagging pipe. In the 'Cold Water Reactor', The heat exchanger contains the water which is used as the expanding/contracting force to produce energy. The heat exchanger is placed outdoors where air can pass over it allowing heat to transfer from the environment.
To accomplish B, there are a variety of different methods. A mechanical device is required that can harness the expanding/contracting force of the water as it freezes and melts. I have come up with four possible methods that I'll describe further on down the page.
To make effective use of these devices in an outdoor environment an array of CWRs should be used, or an array of heat exchangers connected to one mechanical device (B), each calibrated to begin producing energy at a different temperature. For example each would have the water in its heat exchanger dosed with concentrations of salt or other chemicals in order to lower its freezing point. One would be calibrated to begin freezing at 0 degrees celsius, one at -2, one at -4, and so on. This way should one cease producing energy, another will be ramping up. They would be calibrated according to the average temperature patterns of the month.
Should temperatures rise back up to a calibrated freezing point of one of the CWRs in the array, the ice inside that CWR would begin melting, creating a vaccum that will allow the device to produce energy during the melting phase as well as freezing. This will occur several times per day as temperatures are always fluctuating, especially between day and night.
As pressure builds inside the heat exchanger caused by the expanding volume of ice, the freezing point of the water will drop at a rate of 1/100th of a degree Fahrenheit for every additional atmosphere of pressure. The rate of the drop of the freezing point is small enough that very large levels of pressure can be built up without decreasing the melting point by a large amount, thereby allowing a CWR to power a large load producing a greater amount of electricity.
Many hundreds or even thousands of megawatts can be produced from such devices. I believe these devices are most effective for power generation on a large scale.
The question has been posed to me that this method may not be as effective due to the effects of global warming, though I believe a 1 or 2 degree rise in average global temperatures would not be enough to make this source of energy significantly less effective.
There are many places on earth where this method of power generation can be useful. To find out more about the weather in your region, I highly recommend you visit this site:
NASA Surface Meteorology and Solar Energy
I've summed up the basics of this method, so if you wish to read in a bit more detail, please continue. :)
Here is the remaining part of a document where I describe four approaches to convert the slow moving force from the expanding/contracting volume of the catalyst into a faster moving force so that electrical energy can be produced:
Included with these four approaches are four simple drawings in DWG format which are
available here for download. I recommend you view them to get a better picture of the following approaches.
Also I'll include the full
document file.
Approach A: pic
1. Heat Exchanger
A heat exchanger containing the chemical catalyst (H2O) placed in the outside environment where it is exposed to low atmospheric temperatures. The heat exchanger will contain many pipes or vessels of which the sum of the pipes/vessels may be several hundreds or thousands of feet. The heat exchanger must be capable of handling high levels of pressure, and have a large surface area for efficient heat transfer.
2. Hydraulic Cylinder
Connected to the heat exchanger, the cylinder must have a volume large enough to contain 9.4 percent of the water inside the heat exchanger. The cylinder contains a piston with a shaft.
3. Gear-Train
The cylinder shaft will be connected to a gear-train or similar device that converts the slow moving expansion of the cylinder into a higher and more useful speed so that electrical energy can be produced.
4. Generator
Connected to the end of the gear train where there is a fast rotational speed is a generator to convert the mechanical rotational energy of the gear-train into electrical energy.
As the temperature surrounding the heat exchanger drops to levels where the water inside the heat exchanger begins to freeze, the water will be pushed into the cylinder and force the piston to move as pressure builds inside the heat exchanger. Pressure will build inside the heat exchanger because the forming ice is increasing in volume by 9.4 percent compared to water.
The gear-train will cause an opposition force to the expansion of the cylinder further increasing the pressure inside the heat exchanger.
Approach B: pic
1. Heat Exchanger
For same purposes as approach A.
2. Flow Restrictive Passage
A pipe connected to the heat exchanger regulated by a flow control valve allowing water to flow past at specific pressures. The passage and control valve regulates the pressure build-up inside the heat exchanger, increasing the speed of the water flow to a useful amount.
3. Turbine Generator
A turbine connected after the control valve which will rotate as the water is forced through at a useful speed, powering a generator to produce electrical energy.
4. Holding Tank
Connected after the turbine is a reservoir that will hold unfrozen water that is forced in from the heat exchanger.
As the temperature surrounding the heat exchanger begins to drop to levels where the water inside the heat exchanger begins to freeze, the water will be forced to overflow into the flow restricting passage at a higher and useful speed moving the turbine and powering the generator. The flow control valve regulates the pressure built up inside the heat exchanger, and the speed of the water rotating the turbine, thereby controlling the amount of energy being produced.
Approach C: pic
* I am unsure if this approach actually works due to the turbine design
* You can ignore the unlabeled valves in the diagram
In this design there are two turbines that are water tight, so that water in each chamber of the turbine is isolated from the neighboring chamber. There are also valves (float switch symbols) that displace water with air in the turbines. There is a holding tank suspended above the heat exchanger and between the two turbines. The turbines are connected to a shaft that rotates a large generator at a relatively low RPM.
Freezing Process
1. Open Valve 1 and Valve 2. Valve 3 is closed.
2. Ice forms in heat exchanger, forces unfrozen water into turbine A. The air in turbine A is forced out of the device via Float Valve A. This valve closes when the turbine chamber is filled with water. The force of the water causes the turbine to rotate, moving the large generator.
3. Cycle repeats.
Thawing Process
1. Open Valve 1 and Valve 3. Valve 2 is closed.
2. Ice in heat exchanger begins to melt, creating negative pressure on the heat exchanger. Water in chamber of turbine 2 containing Float Valve B is drained back into heat exchanger by suction, and displaced by outside air. Float Valve B then closes once water is drained in that chamber.
3. Suction causes Turbine B to rotate in same direction as when freezing, moving the large generator. The air in the turbine chamber escapes once it reaches the holding tank, and is displaced by water.
4. Cycle repeats.
This design avoids the use of pistons or gear trains. It can handle a much larger amount of water and pressure than those types of designs due to limitations on how large a piston can be made, and losses from gear trains. It moves a much larger load since all pressure can be harnessed from the air tight turbine. The design does not require a fast rotation. It is better suited for large scale power generation.
Approach D: pic
* View Approach D in the DWG file
Heat Exchanger
For same purposes as approach A.
Flow Restrictive Passage
For same purposes as approach B, though this design does not require fast flowing water; it rotates the generator at a low RPM as in approach C.
Retracting Turbine Mechanism
This is a turbine with retracting and extending paddles working similar to an escalator. As the paddles rotate from the water force, they also extend to create a water tight chamber. As water flows to or from the heat exchanger, it pushes the paddles that are fully extended since they are water tight. Connected to the retracting turbine mechanism in the centre of the device is the turbine shaft. The shaft is rotated by the retracting turbine mechanism. The retracting turbine mechanism ensures a high effiency of energy transfer to the generator.
Generator
A large generator connected to the turbine shaft, and rotates at a low RPM.
Holding Tank
For the same purposes as the other designs.
Approach D is as efficient as approach C and would work well for the same reasons, but would likely be more costly than approach C because of complexities in the design of the Retracting Turbine Mechanism.
*In each approach, an extra cylinder may be placed after the heat exchanger to separate the two main areas. With the mechanical area filled with hydraulic fluid instead of water directly from the heat exchanger.
For all approaches, as the pressure builds the freezing point of the water will drop at a rate of 1/100th of a degree Fahrenheit for every additional atmosphere of pressure. The rate of the drop of the freezing point is small enough that very large levels of pressure can be built up without decreasing the melting point by a large amount, thereby producing a greater amount of electricity.
When the water inside the heat exchanger has completely frozen, the device will cease producing energy until the temperature rises and the ice begins to melt. As the ice melts, for approach A the vacuum inside the heat exchanger will enable the cylinder and gear-train to move in the opposite direction as the ice converts into water which is at a higher density than ice; for approach B, C, and D, as the ice converts into water, a vacuum will force the water inside the holding tank to flow in the opposite direction back into the heat exchanger. Therefore energy can be produced during freezing and melting phases for both approaches.
Ideally freezing of water inside the heat exchanger will be uniform, though to avoid forming ice from blocking water flowing into the cylinder/flow restrictive channel, the vessels of the heat exchanger could be made slightly conical, where the vessels are wider at the cylinder/flow restrictive channel and narrow at the opposite end so that more ice forms at the narrow end before the wider end.
The temperature at which H2O changes state into ice/water can be changed to suit the temperature characteristics of an environment and produce energy over a longer range of time. Using anti-freeze chemicals such as concentrations of salt, the freezing point of the water inside the heat exchanger can be lowered. By setting up an array of these energy devices, each with a heat exchanger calibrated to have a different melting point than the next, a larger more constant amount of energy can be harnessed as temperatures fall over that range; at least one of the devices will be working fully at all times.
This energy device is useful in climates where winters are long and temperatures often fall below freezing. The energy device works during times as temperatures are raising and falling -which is at the same time that the energy load for heating buildings is increasing.
Some other possible names for this type of energy device:
- Differential Pressure Reactor
- Temperature Fluctuation Reactor
- Cold Weather Reactor
Example for A - Calculating energy required to produce electrical energy, neglecting losses of gear-train and generator.
Work = Force * Distance
Power = Work / Time
A heat exchanger where the sum of its channels are 1000' by 1', filled with water. (approx 288 000 in^2 of surface area)
Once water inside the heat exchanger freezes, total length now 1094 feet of which 94 feet (28.65 m) have expanded into the cylinder. (Ice 9.4% more volume than water)
Gear train requires a force of 10 million pounds or 44 482 000 Newtons to work.
Temperature drops below freezing, water inside heat exchanger takes 2 hours to freeze (7200s).
Pressure Buildup = GearTrain Force / Heat Exchanger Area = 10 000 000lb / 288 000 in^2
= 34.7 PSI
= 2.36 Atmospheres (1 Atmosphere = 14.7 PSI)
Freezing Point = Atmospheric Freezing point – (Heat Exchanger Pressure * 0.01)
= 32degF - 2.36ATM * 0.01
= 31.98degF
Power = Work / Time = ( 44 482 000N * 28.65m ) / 7200s = 177 KW