What is a thermal machine?

The purpose of a thermal machine is transform heat into work. For that we can use a heat substance like air or gasoline and that will do some thermal transformations in a cyclically way.



Thanks to those transformations the substance absorb the heat and turn it into work.




As we know, the machine works in a cyclically way so the change in the internal energy is null.Here we can apply work´s principle:

The work produced in a period of time is called "potency", and is defined as:

The purpose of a thermal machine is to increas the work produced and the heat absorbed, that is wtaht we call "efficiency". The work always going to be lower that the heat absorbed, so de efficienty of the machine always going to be lower than one.

Normally the efficienty is expressed in percentage. Also the most common machines has a percentage of 20%.

First Thermodynamics Law

First Thermodynamics Law

Where did all of this come from?

Thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy. In particular, it describes how thermal energy is converted to and from other forms of energy and how it affects matter. The fundamental principles of thermodynamics are expressed in four laws.

Now we will review the first one...

 
E2 - E1 = Q - W
We have emphasized the words "into" and "by" in the definition. Heat removed from a system would be assigned a negative sign in the equation. Similarly work done on the system is assigned a negative sign. 

Thermal Mchines in the industry

An example of thermal machines in industry can be seen in the following company:

Festo AG & Co. KG (Esslingen)

Not only does this company provide solutions for industrial automation but also they are innovating with their very own energy concept.  Festo runs the largest solar adsorption cooling machine of Europe at its head offices in Germany. In Esslingen (which is the city where the company is located) the solar thermal system cools and heats the office buildings with a solar-thermal process making a significant contribution to the reduction of CO2 emissions and to the protection of the environment and resources.

How do they do it?

As we all know the conventional air conditioning systems work with electricity, the problem is that these systems are driven by compressors that require more energy to cool the air than needed when the natural air substracted from the atmosphere is warmer than usual as in summer.

So what they do is that they receive solar energy which the put through a thermal driven cooling process and what they get is the needed energy to have cold water and conditioned air. 

The principle of solar cooling is to utilise the solar energy that is available in abundance during the hot months to cool buildings, and its advantages are quite obvious, as the demand for air-conditioning increases the solar energy also increases.

Depending on the application, different processes can be used for solar cooling.The air-conditioning system used by Festo is a closed system that contains water as a refrigerant in its circulation system. The cooled-down air is then distributed in the building through a separate circulation system.The solar thermal collector can be used for cooling in summer, as well as for supporting heating in winter.

Thermal Machine

What is a thermal machine?

A thermal machine is a device capable of transforming thermal energy into mechanic energy to make something work. In other words a thermal machine is a perfect way to produce energy in a green way.

Some examples of thermal machines are the solar panels, steam turbines, Wankel motors, and steam engine. 

There are two ways to input the thermal energy in these machines, the natural ways like solar energy and the artificial ways like burning fossil fuels to produce heat.

In order to understand better how the thermal machines work, here is a little video about how a solar panel system work.

 

Welcome :)

This is our blog for Physics class and on this blog is going to show different kind of thermal machines and how they work, all that in a fun and dynamic way and that way will be more easy to understand what they are.