Types of Thermodynamics Systems

Introduction

System: 

                 A quantity of matter or a region in space under consideration

Surroundings:

                       Mass or region outside the system

Boundary :

                   The surface that separates system and surroundings  

Types of Thermodynamics Systems

There are three types of systems in thermodynamics: open, closed, and isolated.

Closed system:

A system which can exchange only energy with its surroundings, not matter. If we put a very tightly fitting lid on the pot from the previous example, it would approximate a closed system.

Open System:

A system which can exchange both energy and matter with its surroundings. The stovetop example would be an open system because heat and water vapor can be lost to the air.

Closed system:

A system which can exchange only energy with its surroundings, not matter. If we put a very tightly fitting lid on the pot from the previous example, it would approximate a closed system.

Isolated System:

                             A system that cannot exchange either matter or energy with its surroundings. A perfect isolated system is hard to come by, but an insulated drink cooler with a lid is conceptually similar to a truly isolated system. The items inside can exchange energy with each other, which is why the drinks get cold and the ice melts a little, but they exchange very little energy (heat) with the outside environment. 

Turbine and its Classification

Turbine

Turbine is a device that extracts energy from a fluid (converts the energy held by the fluid to mechanical energy)

• Pumps are devices that add energy to the fluid (e.g. pumps, fans, blowers, and compressors)  
• Hydroelectric power is the most remarkable development pertaining to the exploitation of water resources throughout the world.
• Hydroelectric power is developed by hydraulic turbines which are hydraulic machines.
• Turbines convert hydraulic energy or hydro-potential into mechanical energy.
• The mechanical energy developed by turbines is used to run electric generators coupled to the shaft of turbines.
• Hydroelectric power is the cheapest source of power generation.

  Classification of turbines

 1: On the basis of hydraulic action or type of energy at the inlet

•  Impulse Turbine (Pelton Wheel)
•  Reaction Turbine (Francis Turbine)

 2: On the basis of the direction of flow through the runner

• Tangential flow turbine (Pelton)
• Radial flow turbine (Francis )
• Axial Flow Turbine (Kaplan)
• Mixed flow turbine (Modern Francis)  

3: On the basis of the head of water

• High head turbine (Pelton, H>250m)
• Medium head turbine (modern Francis, 60-250m)
•  Low head turbine (Kaplan, <60m)

4: On the basis of specific speed Ns of the turbine

•  Low specific speed (Pelton, 10-35)
•  Medium (Francis, 60-400)
• High specific speed (Kaplan, 300-1000)  

Why Are Tires Black? The Science Behind Rubber Tires

Have you ever wondered why tires are black, even though natural rubber is white? The answer lies in the addition of an ingredient called carbon black, which transforms the color of rubber and significantly improves its performance.

The Natural Color of Rubber

Rubber, in its natural state, is actually milky white. This may come as a surprise since we're so accustomed to seeing black tires on our vehicles. So why aren't tires white?

The Role of Carbon Black

In the early 19th century, manufacturers discovered that adding carbon black to rubber produced a much stronger and longer-lasting tire. Here’s how carbon black works:

• Reinforcing Filler: Carbon black acts as a reinforcing filler in rubber, which increases the durability and strength of the tire. This means the tire can withstand more wear and tear over time.
• Heat Conduction: Tires generate a lot of heat while driving, especially in the tread and belt areas. Carbon black helps conduct heat away from these areas, reducing the likelihood of damage and extending the tire’s lifespan.

Why Are Tires Black?

In summary, tires are black because carbon black is added during the manufacturing process. This ingredient not only changes the color of the rubber but also makes the tires stronger, more durable, and longer-lasting.

So, the next time you look at your car’s tires, remember that their black color is a key part of what makes them safe and reliable on the road!

Casting and Forging difference

Casting vs Forging

Casting:

Casting is a process in which molten metal flows by gravity or other force into a mold where it solidifies in the shape of the mold cavity

• The term casting also applies to the part made in the process
• Steps in casting seem simple:

1. Melt the metal
2. Pour it into a mold
3. Let it freeze

Advantages of Casting:

•       Can create complex part geometries
•       Can create both external and internal shapes.
•       Some casting processes are net shape*; others are near net shape.
•       Can produce very large parts.
•       Some casting methods are suited to mass production.
•       Suitable for any metal that can be heated to a liquid.

  Disadvantages of Casting:     

•       Limitations on mechanical properties.
•       Poor dimensional accuracy and surface finish for some processes; e.g., sand casting.
•       Safety hazards to workers due to hot molten metals.
•       Environmental problems.

Forging:

                Deformation process in which work is compressed between two dies using either impact or gradual pressure to form the part.

•        Oldest of the metal forming operations, dating from about 5000 BC.
•        Components: engine crankshafts, connecting rods, gears, aircraft structural components, jet engine turbine parts. 
•         Also, basic metals industries use forging to establish a basic form of large parts that are subsequently machined to final shape and size.  
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Classification of Forging Operations:

                 1. Hot or warm forging:

                               Most common, due to the significant deformation and the need to reduce strength and increase the ductility of work metal.

               2. Cold forging:   

                      Advantage: increased strength that results from strain hardening. Cold forging is generally preferred when the metal is already a soft metal, like aluminum.  

Advantages of Forging:

• It produces a tougher product compare to other.
• The product made by forging has high impact or tensile strength.