Solar pond pump-features of solar fountain pump

What is a solar pond pump?

A solar pond pump takes the solar energy from a PV or Photovoltaic panel. Sometimes these pumps are designed as a fountain and sometimes called the solar fountain pump.

A solar powered pond pump can be a great alternative to the conventional pumps. And eventually in the long run it will save the expenses. For the perfect functioning of solar pumps the solar panel should be placed in a location which gets decent sun light.

The size and standard of the solar panel defines the power collected from the solar powered pond pumps. In most cases the power output is moderates and not suitable for big projects. And these devices will not work after sunset. But sometimes they have batteries which keep them running for some hours. 
These are some links where you will find some good solar pumps:

• Solar Pond Pump and Fountains Prices 

The conventional pumps are very much cheap compared to the solar pumps and solar panels. So if you have electricity then conventional mains pumps are the best choice. But I must say if you make the perfect calculations then you will find that solar powered fountain pump is an affordable option. So is it possible to get cheap pond pumps? The answer is yes and no! If you consider the initial cost of the solar pump and solar panel then you will find it very expensive. But when you will compare this cost with the cost of wiring, power lines and most importantly time spent then you will find that solar powered fountain pump is quite affordable with a reasonable price. Solar pond pump works better when the sun is shining the most and certainly you need more water flow when the sun is very hot. So it is reasonable to use solar pumps. 

Features of a solar pond pump

Advantages

• No running cost
• Easy setup procedure
• Great for use in remote areas.
• Perfect for fountains.
• Very little noise.
• No environmental pollution.
• This setup can be used as a dehumidifier when used in indoors.
• Very little maintenance needed.
• Solar pond pump has a relatively long life.

Disadvantages

• Power output is low. Water flow rate is also low in solar pond pumps. 
• Solar pond fountain is not suitable for large projects.
• Cloudy days can cause less power output.
• Expensive.
• Very few companies produce solar pond pump. So the options are limited.
• Cannot be used during night time without battery support.

Features of solar fountain pump

Sometimes the solar panel includes the design of the fountain. So the fountain must be placed in a sunny place. It ensures enough sunlight to fall on the panel.

In some cases the panel and fountain is in separate locations. A cord is used to join the two. As long as the panel is getting enough sunlight the fountain can be place anywhere.

Finally I can say that this fountain pumps have their pros and cons. But in the long run these can be proved very beneficial. Here’s a demo of solar pond pump. 

Please read these article for further study: 

Geothermal Energy Pros and Cons 

Fixed Dome Type Biogas plant construction 

What is the cheapest source of renewable energy ? 

Advantages and disadvantaged of hydroelectric power

Renewable Energy Sources - Graphical Presentation

Different types of nuclear reactors 

Different energy sources - units and conversions 

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Every type of energy has its own advantages and limitations. In this article I will discuss about the pros and cons of geothermal energy.

What is Geothermal Energy?

The earth is a heat reservoir of heat energy in the form of molten interior. Surface manifestation of this heat energy is indicated by hot water springs and geysers discovered at several places. Heat can be experienced from the temperature rise of the earth’s crust with increasing depth below the surface. Radial temperature gradient increases proportionally to depth at a rate of 30 degree Celsius per kilometer. At a rate of 3-4 kilometers water bubbles up; while at a depth of 10-15 kilometers the earth’s interior is as hot as 1000 to 1200 degrees. The core of the earth consists of a liquid rock known as Magma having a temperature about 4000 degrees.

The geothermal heat is transferred to the underground reservoir of water which also circulates under the earth’s crust. Its heat dissipates into the atmosphere as warm water and steam vents up through the fissures in the ground as hot springs and geysers. Limitless heat generation by the magma and by radioactive decay of unstable elements like K40, Th232 and U235 which are abundant in the earth’s crust are forms of geothermal energy and considered as renewable energy resource. 

Before analyzing geothermal energy pros and cons one must have knowledge about structure of the earth’s interior. The earth consists of a series of concentric shells. Its internal structure can be divided into three parts – Crust, Mantle and Core. 

The crust

The solid crust of earth is 70-100km thick and can be divided into continental crust, 20-65 km under the continents and oceans crust 7 km under the ocean basins. The study of the seismic waves has indicated that the earth’s crust underneath continents is thicker than that of that underneath the oceans as seismic waves travels faster in oceanic crust than in continental. The oceanic crust consists of low density rocks (basalts) whereas the continental crusts largely contain the granite. Enormous amount of geothermal energy can be got from the cracks in the earth’s crust. Whenever a geothermal site is drilled. Steam, hot water gush out through the drilled hole and become a source of geothermal energy. 

The mantle 

 For the utilization of geothermal energy we must gain some basic knowledge about the layer underneath the crust. It is called the mantle. The upper rigid part of the mantle extends up to 100km below the separating crust and contains mainly iron and magnesium. The crust and upper mantle form ‘lithosphere’. The lower mantle extending up to 2900 km below the earth’s surface is less rigid and is hotter. This is known as ‘asthenosphere’ and is capable of being deformed. The phenomena of plate tectonics i.e. the movement of the earth’s crust is caused by the movement of the lithosphere over the asthenosphere. 

The core 

It forms about 35% of the earth’s mass and has a radius of 3500km. The outer core is molten or liquid while the inner core (radius 1170 km) is believed to contain nickel-iron alloy. The hot molten rock of the mantle is called magma. The outer core being in the molten state behaves like a liquid responsible for all the earthquakes and volcanic activities. A thermal gradient is created from core to mantle and earth crust. The outward of heat energy from molten hot interior of the earth to the cooler surface makes the earth to operate like a heat engine. That’s one of the advantages of geothermal energy. 

Geothermal Energy Pros and Cons

Actually geothermal energy is a great source of heat found under the earth’s crust. It has its own advantages and disadvantages. Already fossil fuels have started to diminish. And in the future geothermal energy is expected to produce a great amount of power with a relatively cheap rate. Despite all this pros geothermal energy is not used widely because of this problems. 

Geothermal energy disadvantages 

 Geothermal energy is not wide spread source of energy because to utilize geothermal energy perfect equipment and infrastructure is needed. So world wide installation of geothermal plants is not possible. For a efficient geothermal plant thousands of skilled manpower is needed. 
The production of electricity from geothermal plant needs high installation cost because of setting up miles long pipe underneath the earth's crust. To get geothermal energy from a plant high skilled staff in needed which yields high cost. 
Initial research is needed to be done before a setting up a geothermal plant because the natural steam production can be reduced in course of time. Geothermal fields can die and can cause a great deal of loss to the company. 
All the countries cannot use geothermal energy because all countries fall in the geothermal field region. It is a great geothermal disadvantage. 
While digging a geothermal field poisonous gas can come out from the site. This can cause great harm to the life of people and animal. This can also pollute the atmosphere. 
geothermal disadvantages include the problem of transportation. It cannot be transported easily. Once the geothermal energy is extracted from the field it can only be used in the plants of its surroundings.  

 This were the major geothermal energy disadvantages. 

Geothermal energy advantages

• The reliance on the fossil fuel will be drastically reduced if the proper utilization of geothermal energy is ensured. This will help the countries which have to bought a great amount of fossil fuel every year. 
• The less the use of the fossil fuels the less the pollution of the environment. It is the most important advantage of geothermal energy. 
• The running cost of geothermal energy is very low. The price is 80% less than the running cost of plant run by fossil fuels. 
• Geothermal energy can used directly. From an ancient time people are relying on the geothermal energy for heating, bathing and washing. 
• If geothermal energy is properly utilized it will create a great impact on the world economy and creat job opportunities for thousands of people. 

Finally we can say that the world energy consumption is rising. The demand for different energy sources are also increasing. In this situation the use of renewable energy with innovation can solve all the problems. So all the scientists and engineers try to know about geothermal energy pros and cons and make the world a better place.

For more information read :

• Geothermal Energy Pros and Cons 
• Renewable energy sources 
• Flash Steam power plant run by geothermal energy 
• Energy sources and unit conversions 
• Nuclear Power plant : Nuclear reactors 
• Biogas plant construction 
• What is the cheapest source of renewable energy ? 
• Advantages and Disadvantages of hydroelectric power 
• Solar pond pump and fountain features 
• Biomass - pros and cons 

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Important Dimensionless Groups in Fluid Mechanics–Reynolds Number

Variables needed for getting dimensionless groups  

In most of the fluid phenomena the following variables may be important

- Length. L

- Acceleration due to gravity, g

- Mass density, ρ

- Velocity, V

- Pressure, p

- Viscosity, µ

- Surface tension, σ

-Velocity of sound C


Forces needed to get the Dimensionless Numbers in Fluid Mechanics 

The following forces can be formed from these variables.

Inertia force = mass x acceleration = ρL3 x(V/t)= ρL2V x(L/t)= ρL2V2

Viscous force = area X shear stress = L2 x µ x (V/L) = µVL

Gravity Force = mass X acceleration due to gravity = ρL3g

Pressure Force = pressure x area = pL²

Elastic Force = bulk modulus of elasticity X area = E x L² = ρC²L², Since E = ρC²

Surface Tension Force = σL

The following dimensionless groups can be formed by combining inertia force with each of the independent forces.

Reynolds Number in Fluid Mechanics, N_Re

It is the ratio of inertia force and viscous force.

Reynolds number formula,  N_{Re =} Inertia force / Viscous force = ρL²V² / µVL = ρVL/µ 

So , Reynolds number equation = ρVL/µ . For getting Reynold Number using kinematic viscosity we have to divide the dynamics viscosity µ by the density ρ. 

Reynolds number similarity is used when viscous force is predominant. For example, flow through pipes completely submerged flow, flow through venturimeter and orificemeter etc.

Froude Number, Fr

It is the ratio of inertia force to gravity force.

Froude Number , Fr = Inertia Force / Gravity Force =  ρL²V² / ρL³g = V²/Lg

Froude number is used when gravitational force is predominant in the fluid motion. For example open channel flow, wave motion in the ocean, forces on bridge piers and off shore structures.  

Euler Number , E 

It is the ration of pressure force and inertia force.

Euler Number = Pressure force / Inertia Force = pL² / ρL²V² = p/ρV² = F/ ρV²L²

Euler number is important when pressure force is predominant. For example, flow through pipes, flow over submerged bodies, flow of water through orifices and mouthpieces etc.

Mach number, M 

Square root of the ratio of inertia force to the elastic force 

Mach Number = (Inertia force / elastic force)^1/2 =  (ρL²V² / ρC²L²)^1/2 = V/C

The ratio v²/c² is known as Cauchy’s number. Mach number is important in compressible fluid flow at high velocities. For example high velocity flow in pipes, motion of high velocity projectiles and missiles.  

Weber Number, W

It is defined as the ratio of inertia force to the surface tension force.

Weber Number = Inertia force / Surface tension force = ρL²V²/ σL = ρLV²/ σ

Weber number is important when surface tension is important. For example, capillary tube flow, droplet formation, human in blood flow etc.

Please Read : 

• How to read Moody Diagram
• How to solve fluid mechanics problems by moody chart 
• Newton's law of viscosity 
• Methods of Dimensional analysis in fluid mechanics 
• Importance of fluid Mechanics for engineers and physicists 
• Fluid and some of its properties 
• A Complete Guide to Fluid Mechanics 

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Similitude in Fluid Mechanics - Similarity Laws

Similitude in Fluid Mechanics 

There are a lot of advantages of dimensional analysis and similitude in fluid mechanics. With the application of dimensional analysis and similitude or laws of similarity, number of experiments can be reduced. Costs can be reduced by doing experiments with models of the full size apparatus. Performance of the prototype can be predicted from tests made with model. With the help of similarity laws the results obtained from experiments done with air or water can be applied to a fluid, which is less convenient to work with, such as gas, steam or oil.  

Description of Similarity Law for Fluid Mechanics

The similarity relation between a prototype and its model is known as similitude. Types of similarities must exist for complete similitude between a model and its prototype. These are - 

j) Geometric similarity
ii) Kinematic similarity
iii) Dynamic similarity 

Geometric Similarity laws in fluid mechanics 

A model and its prototype are said to be in geometric similarity, if the ratios of their corresponding linear dimensions are equal (such as length, breadth, width etc.) For geometric similarity, the corresponding areas are related by the square of ratio and the corresponding volumes by the cube of the length scale ratio.

 Length scale ratio = l_m/l_p = b_m/b_p = d_m/d_p  

(Length scale ratio)2 = Area-model / Area-prototype = (l_m/l_p )²  = ( b_m/b_p )² = ( d_m/d_p)²

(Length scale ratio)3 = Volume-model / Volume-prototype = (l_m/l_p )³ = ( b_m/b_p )³ = (d_m/d_p )³


Here, l_m,b_m,d_m  are the linear dimensions of the model and l_p,b_p,d_p are the linear dimensions of the prototype.  

Kinematic Similarity/ similitude in fluid mechanics 

A model and its prototype are said to be kinematically similar if the flow patterns in the model and the prototype for any fluid motion has geometric similarity and if the ratios of the velocities as well as accelerations at all corresponding  points in the flow is the same.

Let,

V1 and V2 — velocities of fluid in prototype at points 1 and 2

v1 and v2 — velocities of fluid in model at corresponding points 1 and 2

A1 and A2 — acceleration of fluid in prototype at points I and 2

a1 and a2 — acceleration of fluid in model at corresponding points 1 and 2

Velocity ratio = V1/v1 = V2/v2

Acceleration ratio = A1/a1 = A2/a2

Dynamic Similarity law in fluid mechanics 

A model and its prototype are said to be dynamically similar if the ratio of the forces acting at the corresponding points are equal. Geometric and kinematic similarities exist for dynamically similar systems. 

1onding points are equal. Geometric and kinem

F1 and F2 — forces acting in prototype at points I and 2

 f1 and f2 — forces acting in the model at the corresponding points 1 and 2

Now F1/f1 = F2/f2  = constant

If the dynamic, kinematic and geometric similarities can be obtained then experiments with models can give very accurate results. That's why similitude in fluid mechanics is very important. 

Please read:

• Principles of similitude fir engine design. 
• Methods of Dimensional analysis 
• An Introduction to fluid mechanics 
• A Complete Guide to Fluid Mechanics 

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What is the first law of thermodynamics – definition and equation

Thermodynamics if basically a science of energy. And the definition of energy varies from situation to situation. But in general we can say that energy is the cause of all changes. And this energy situation cannot be explained without thermodynamic laws. And the first law of thermodynamics is the expression which defines the principle of conservation of energy. According to the law of conservation of energy – energy can be transformed from one form to another but cannot be created or destroyed. A term internal energy is often used to explain first law. Read the following article for clear concept about enthalpy, entropy, internal energy, system, boundary and substances. 


Please Read : 
Enthalpy, Entropy and Internal Energy . 
What is system. boundary ans surroundings in thermodynamics ?
What is substance in thermodynamics? 
What is the objective of thermodynamics ? Difference between thermodynamics and heat transfer  

First law of thermodynamics-definitions 

The first law of thermodynamics states that the energy of a system is conserved. It states that

Q-W= de ………………. (1)

Where,

Q is the heat added to the system,

W is the work done on the system

And de is the increase of internal energy of the system. 

First law of thermodynamics is formulated by stating that, increase in the internal energy (de) is got by the difference of heat supplied to the system (Q) minus the work that has been done by the system into its surrounding.

All quantities in Eq. (1) may be regarded as those referring to unit mass of the system. (In thermodynamics texts it is customary to denote quantities per unit mass by lowercase letters, and those for the entire system by uppercase letters. This will not be done here.)

The internal energy (also called “thermal energy”) is a manifestation of the random molecular motion of the constituents. In fluid flows, the kinetic energy of the macroscopic motion has to be included in the term ‘e’ in Eq. (1) in order that the principle of conservation of energy is satisfied. For developing the relations of classical thermodynamics, however, we shall only include the “thermal energy” in the term e in explaining 1st law of thermodynamics.So in this section we see how energy is conserved in the first law of thermodynamics.

Difference between heat and internal energy in first law of thermodynamics

It is important to realize the difference between heat and internal energy. Heat and work are forms of energy in transition, which appear at the boundary of the system and are not contained within the matter. In contrast, the internal energy resides within the matter. If two equilibrium states 1 and 2 of a system are known, then Q and W depend on the process or path followed by the system in going from state 1 to state 2.

The change de = e₂ – e₁, in contrast, does not depend on the path. In short, e is a thermodynamic property and is a function of the thermodynamic state of the system.

Thermodynamic properties are called state functions, in contrast to heat and work, which are path functions.

First law of thermodynamics-equation

Frictionless quasi-static processes, carried out at an extremely slow rate so that the system is at all times in equilibrium with the surroundings, are called reversible processes. The most common type of reversible work in fluid flows is by the expansion or contraction of the boundaries of the fluid element. Let v = I/p be the specific volume, that is, the volume per unit mass. Then the work done by the body per unit mass in an infinitesimal reversible process is -pdv, where du is the increase of u.

The first law (Eq. (1)) for a reversible process then becomes

de = dQ - pdv,  (2 )

Provided that Q is also reversible.

Equations of State for thermodynamics first law

In simple systems composed of a single component only, the specification of two independent properties completely determines the state or the system. We can write relations such as

p = p (v, T) (thermal equation of state),

e = e (p, T) (caloric equation of stale).  (3)

Such relations are called equations of state. For more complicated systems composed of more than one component, the specification of two properties is not enough to completely determine the state. For example, for sea water containing dissolved salt, the density is a function of the three variables, salinity, temperature, and pressure.

Specific Heats explaining the 1^st law of thermodynamics

Before we define the specific heats of a substance, we define a thermodynamic property called enthalpy as

H = e + pv ... (4)

This property will be quite useful in our study or compressible fluid flows.

For single-component systems, the specific heats at constant pressure and constant volume are defined as

C_p = (dh/dT)_p ... (5)

C_v = (de/dT)_v   ... (6)

Above mentioned equations mean that we regard h as a function of p and T, and find the partial derivative of h with respect to T, keeping p constant. Equation (6) has an analogous interpretation. It is important to note that the specific heats as defined are thermodynamic properties, because they are defined in terms of other properties of the system. That is, we can determine Cp and Cv when two other properties of the system (say, p and T) are given. Thus in the understanding of the first law of thermodynamics specific heat certainly have some significance.

For certain processes common in fluid flows, the heat exchange can be related to the specific heats. Consider a reversible process in which the work done is given by p du, so that the first law of thermodynamics has the form of Eq. (2). Dividing by the change of temperature, it follows that the heat transferred per unit mass per unit temperature change in a constant volume process is

(dQ/dT)_v = C_v

This shows that CvdT represents the heat transfer per unit mass in a reversible constant volume process, in which the only type of work done is of the pdv type. It is misleading to define C = (dQ/dT) without any restrictions imposed, as the temperature of a constant-volume system can increase without heat transfer, say, by turning a paddle wheel.

In a similar manner, the heat transferred at constant pressure during a reversible process is given by

(dQ/dT)_p = C_p

The first law of thermodynamics state the key concepts of internal energy, heat and work done. Many sign conventions are used for expressing the first law of thermodynamics equation. These are sign convention of Clausius, sign convention of IUPAC and quasi-static process.  

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Fixed Dome type – Janata Model Biogas Plant Construction

Biogas can be a great alternative of fossil fuels. It is already in use in many rural areas. Biogas plants use animal waste, plant waste and human waste. All this wastes have great combustible property. Biogas is an excellent renewable energy source. It is produced by the digestion of waste materials by the means of anaerobic reaction. Anaerobic means the absence of Oxygen. In most of the rural areas cow and buffalo dungs is used as biomass fuel for producing gas. The typical composition of biogas is

Methane - CH₄  (55 - 65 %)
Carbon dioxide CO₂  (30-40%) 

H_{2 ,} H₂S , N₂      (< 10%) 

Biogas Technology involves the bacterial breakdown of the waste materials to produce Methane, Carbon Dioxide and Water . The process involves the following three steps - 

Hydrolysis 

Organics materials contains mainly carbohydrate mainly in the form of cellulose, hemicellulose and lignin. These have very complex structure which is not suitable for absorption. So these matters are converted into simple soluble materials by the action of celluolytic or hydrolytic bacteria. Concentration of bacteria in the organic materials, temperature and pH controls the rate of hydrolysis. pH between 6 to 7 and temperature between 30-40 degree Celsius is good for bacteria to work. 

Acid Formation 

Simple organic materials are turned into acid by acetogenic bacteria. 

Methane Formation 

Methanogenic bacteria turns the acid into methane, carbon dioxide, hydrogen, nitrogen and oxygen. The methane content is 60%. It has high calorific value. Very good for combustion and producing energy. 

Biogas plants 

Biogas plant converts the organic wastes like dung, human waste and plant wastes into a inflammable and it also produces a high quality organic manure as a by product. Most popular two designs of biogas plant is 

1. Fixed Dome Type Biogas plant (Janata Model) (Operates in constant volume)

2. Floating Drum type Biogas plant. (Operates in constant pressure)

In this article I will discuss about the first one - The Fixed Dome type or Janata Model biogas plant. 

Fixed Dome Type Biogas Plant - Janata Model 

This type of biogas plant is very economical is design. It works with the constant volume principle. The main structure is made up of brick and cement masonry. This type of plant doesn't have any moving parts so it is safe from wear and tear. The operating pressure varies from 0 to 100 cm of water column. It is also known as Janata model.  

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