Investigating hypothesis using change in temperature

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Introduction

Did you know that 85% of the energy we use comes from fossil fuels? Fossil fuels are energy sources such as coil, oil and natural gas. But the common issue presented to us is that fossil-fuels are running out.

Renewable energy, as a wonderful option for fossil fuels, is recommended by everyone who cares about the future of human. There are some well known types of renewable power such as Solar Power, Hydropower, Geothermal Power and Wind Power. From this we can see that almost every renewable power is related to an unlimited natural substance.

Temperature, such a fundamental component in every dynamic system, plays a critical factor in the physics of virtually every equation. The ability to control temperature can be the powerful enabling solution for applications ranging from molecular diagnostics to electronics manufacturing.

As a matter of fact, almost every equipment human created has a problem of efficiency. As the biggest enemy, heat energy lost in surrounding is almost impossible to collect. However, here is a hypothesis that we can get electricity by using the change in temperature to generate. The change in temperature can be found everywhere on the earth. So, if there were some way to collect the energy from the temperature changing around us, this may solve the energy crisis.

Body

Validity of the theory

The idea

  1. The idea is to build a collector to absorb energy from air outdoor and transmit it to clerical energy.
  2. The way is using difference in temperature between day and night. In other words, when the surrounding temperature rises in the day, the substances in the collector will expand. Collecting this part of mechanical energy and convert it to clerical energy.

Where the idea came from

  1. Atmos clock
  2. Atmos is the brand name of a mechanical clock manufactured by Jaeger-LeCoultre in temperature changes in the environment, and can run for years without human intervention.

    Its power source is a hermetically sealed capsule containing a mixture of gas and liquid ethyl chloride, which expands into an expansion chamber as the temperature rises, compressing a spiral spring; with a fall in temperature the gas condenses and the spring slackens. This motion constantly winds the mainspring. A variation in temperature of only one degree in the range between 15 and 30 degrees Celsius is sufficient for two days' operation.

    One more step, we can convert it into clerical energy.

  3. The conversation of energy :
  4. The law of conservation of energy states that the total amount of energy in a closed system remains constant. A consequence of this law is that energy cannot be created nor destroyed. The only thing that can happen with energy in a closed system is that it can change form, for instance kinetic energy can become thermal energy.

    For instance, the production of electrical power with fossil fuels can be demonstrated by looking at the energy conversions in a coal-fred power station using a Sankey energy transfer diagram as shown below.

From the diagram we can see that heat energy lost in surrounding, mentioned in the introduction section, will not disappear but transmit to other form of energy. The biggest waste for this process is the energy lost in substance around it, the cooling towers.

Of course, we can find a way to collect the energy from cooling tower and convert it to electrical energy. Moreover, every moving thing on the land is releasing heat energy to our surrounding-air. Similarly, if we can find a way to collect the energy from air, we can find another unlimited resource.

As a matter of fact, the temperature around us is changing all the time and in some area the change of it is pretty large.

We can use the First Law of Thermodynamics to see the fundamental of collecting energy from temperature change.

The First Law of Thermodynamics

The first law of thermodynamics, an expression of the principle of conservation of energy, states that the increase in the internal energy of a system is equal to the amount of energy added by heating the system, minus the amount lost as a result of the work done by the system on its surroundings.

In the following equation

Euniv = Esys + Esurr = 0

A more useful form of the first law describes how energy is conserved. It says that the change in the internal energy of a system is equal to the sum of the heat gained or lost by the system and the work done by or on the system.

Esys = q + w

The sign convention for the relationship between the internal energy of a system and the heat gained or lost by the system can be understood by thinking about a concrete example, such as a beaker of water on a hot plate. When the hot plate is turned on, the system gains heat from its surroundings. As a result, both the temperature and the internal energy of the system increase, and deltaE is positive. When the hot plate is turned off, the water loses heat to its surroundings as it cools to room temperature, and deltaE is negative.

There are five types of thermodynamic processes

  1. Isobaric process
  2. Isochoric process
  3. Isothermal process
  4. Isentropic process
  5. Adiabatic process

In our case, isobaric process is the fundament of energy collector.

Isobaric process

An isobaric process is a thermodynamic process in which the pressure stays constant: ?p = 0. For ideal gas, the equation of isobaric process is V/T=constant. The isobaric process becomes a bar which parallel to the V axis.

In conclusion, the fundamental of this collector is base on the isobaric process in the thermodynamics. But for our case, the piston cannot be frictionless. So under the condition of PV/T= constant, PV will increase when T increases.

In reality, P≠0and V≠0. F=Ap, V=AS, Therefore W=FS=Ap* V/A=pV

That is to say, when the temperature rises in the day, the work done by this collector will increase. Theoretically, this equipment is able to collect the heat energy and convert it into mechanical energy.

Investigation of constructiveness

The substance we use:

Thermal expansion

Thermal expansion is the tendency of a matter to change in volume in response to a change in temperature. When a substance is heated, its particles begin moving and become active thus maintaining a greater average separation. Materials which contract with increasing temperature are rare; this effect is limited in size, and only occurs within limited temperature ranges. The degree of expansion divided by the change in temperature is called the material's coefficient of thermal expansion and generally varies with temperature.

When the temperature of a substance changes, the energy that is stored in the intermolecular bonds between atoms changes. When the stored energy increases, so does the length of the molecular bonds. As a result, solids typically expand in response to heating and contract on cooling; this dimensional response to temperature change is expressed by its coefficient of thermal expansion (CTE).

Different coefficients of thermal expansion can be defined for a substance depending on whether the expansion is measured by:

  • linear thermal expansion (CLTE)
  • Area thermal expansion
  • Volumetric thermal expansion.

These characteristics are closely related. The volumetric thermal expansion coefficient can be defined for both liquids and solids. The linear thermal expansion can only be defined for solids, and is common in engineering applications. As a matter of fact, harder materials are more likely to have lower thermal expansion. In general, liquids expand slightly more than solids and gas is most expandable among three.

In this case, the volumetric thermal expansion of gas is our object to investigate.

After check the Matheson Gas Data book, we can see that even though H2 has the highest coefficients of thermal expansion, The critical temperature and working range is too low for the collector. Air probably is the most simple and convincement option with high coefficients of thermal expansion.

The way we generate

Plan A:

How to generate from the mechanical energy

A mainspring is a spiral spring of metal ribbon that is the power source in mechanical watches and some clocks. Winding the timepiece, by turning a knob or key, stores energy in the mainspring by twisting the spiral tighter. The force of the mainspring then turns the clock's wheels as it unwinds, until the next winding is needed. The adjectives wind-up and spring-wound refer to mechanisms powered by mainsprings, which also include kitchen timers, music boxes, wind-up toys and clockwork radios.

Hazards ?

The mainspring contains a lot of energy, which can release suddenly during disassembly if precautions are not taken, causing serious injury. Mainsprings should be 'let down' gently before servicing, by holding the winding key and pulling the click back, allowing the spring to slowly unwind. However, this is the theory for watch. For a generator, this kind of release can be used to generate by electromagnetic induction.

Generator

In electricity generation, an electrical generator is a device that converts mechanical energy to electrical energy. The generator creates electricity by a series of fine wire windings inside a magnetic field, called an armature. As the armature is spun inside this magnetic field by the generator's motor, current and voltage gets generated in those windings of wire and electricity is transferred. That current and voltage will be directly proportional to the speed that the armature spins and to the strength of the magnetic field. Each complete revolution, one complete cycle of alternating current (AC) is developed.This is called a rotating armature.

In this way, we can produce electricity.

Plan B:

Generator

The piezoelectric effect is reversible in that materials exhibiting the direct piezoelectric effect (the production of an electric potential when stress is applied) also exhibit the reverse piezoelectric effect (the production of stress and/or strain when an electric field is applied). For example, lead zirconate titanate crystals will exhibit a maximum shape change of about 0.1% of the original dimension.

The effect finds useful applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies.

By using this way, we can directly convert the mechanical energy into electrical energy.

Any spatially separated charge will result in an electric field, and therefore an electric potential. Shown here is a standard dielectric in a capacitor. In a piezoelectric device, mechanical stress is the cause for the charge separation in the individual atoms of the material, rather than an externally applied voltage.

The way we store electricity

Of course, battery is the best option. But which battery is most suitable for this generator?

Here are some characteristics which should be considered.

  1. low self-discharge rate
  2. long service life
  3. high ability for deep discharge
  4. high charging efficiency
  5. little maintenance
  6. wide range of working temperature
  7. low price

Our option is lead-acid battery.

Lead-acid batteries, invented in 1859 by French physicist Gaston Planté, are the oldest type of rechargeable battery. Despite having the second lowest energy-to-weight ratio (next to the nickel-iron battery) and a correspondingly low energy-to-volume ratio, their ability to supply high surge currents means that the cells maintain a relatively large power-to-weight ratio. These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required by automobile starter motors.

In the charged state, each cell contains electrodes of elemental lead (Pb) and lead (IV) dioxide (PbO2) in an electrolyte of approximately 33.5% v/v (6 Molar) sulfuric acid (H2SO4).

In the discharged state both electrodes turn into lead(II) sulfate (PbSO4) and the electrolyte loses its dissolved sulfuric acid and becomes primarily water. Due to the freezing-point depression of water, as the battery discharges and the concentration of sulfuric acid decreases, the electrolyte is more likely to freeze during winter weather.

The chemical reactions are (discharged to charged):

Because of the open cells with liquid electrolyte in most lead-acid batteries, overcharging with high charging voltages will generate oxygen and hydrogen gas by electrolysis of water, forming an explosive mix. The acid electrolyte is also corrosive.

Practical cells are usually not made with pure lead but have small amounts of antimony, tin, calcium or selenium alloyed in the plate material to strengthen the plates and make them easier to manufacture.

References and bibliography

  • http://courseware.ecnudec.com/zsb/zls/zls12/zls12g/zls12g03.htm
  • www (dot) humanthermodynamics (dot) com/1st-Law-Variations.html Variations of the 1st Law of Thermodynamics, at IoHT.
  • Mayer, Robert (1841). Paper: 'Remarks on the Forces of Nature"; as quoted in: Lehninger, A. (1971). Bioenergetics - the Molecular Basis of Biological Energy Transformations, 2nd. Ed. London: The Benjamin/Cummings Publishing Company.
  • LeCoultre Atmos Clock History
  • Sacks, Adam Michael. "How the Atmos works". The Atmos clock page. http://www.atmosadam.com/howitworks.html. Retrieved 2007-12-08. Detailed drawing of movement, gallery of pictures.
  • Murray, Michael P. (2004). "Mike's Clock Clinic". http://www.atmos-man.com/. Retrieved 2007-12-07. Clock repairer specializes in Atmos, much info on models, part supply, history.
  • http://en.wikipedia.org/wiki/Thermal_expansion
  • Matheson Gsa Data Book

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