What are the basic principles of refrigeration?
To put it simply there are 3 steps by which a refrigerator or a fridge works:
- Cool refrigerant is passed around food items kept inside the fridge.
- Refrigerant absorbs heat from the food items.
- Refrigerant transfers the absorbed heat to the relatively cooler surroundings outside.
What is the working principle of a refrigerator?
Working of Refrigerator : The basics
- The basic principle of refrigerator. The basic principle of refrigeration is simple. ...
- Components of refrigerator and working. An inside view of a refrigerator is shown. ...
- Throttling device. ...
- Evaporator - heat absorption process. ...
- Use of Compressor. ...
- Use of Condenser. ...
- Refrigerator components. ...
- Details of compressor. ...
- Coefficient of performance. ...
What is basic refrigeration system?
The Basic Refrigeration System
- Compressor. Pumps refrigerant:One of the main functions of the compressor is to circulate refrigerant. ...
- Discharge Line. Transports vapor:One function of the discharge line is to carry the high-pressure, superheated vapor from the compressor's discharge valve to the entrance of the condenser.
- Condenser. ...
What is the basic refrigeration cycle?
Working Principle Scheme of Refrigeration Cycle
- Refrigerant is pumped in the refrigeration cycle or circuit.
- It is circulated through refrigerant pipes or tubing.
- It has a very low boiling point & it starts evaporating at normal conditions.
- Refrigerant presents in the evaporator, takes up the heat from adjacent air for evaporation.
- Refrigerant changed its phase from liquid to vapor.
What is the principle used in refrigerator?
Refrigerators work by causing the refrigerant circulating inside them to change from a liquid into a gas. This process, called evaporation, cools the surrounding area and produces the desired effect.
What is the law of thermodynamics for refrigeration?
The second law of thermodynamicsThe second law of thermodynamics claims that it is impossible for heat to spontaneously flow from a cold body to a hot body, but it can move in that way if some form of work is done. This is how the refrigeration process works, and an example can be seen in Figure 1.
What are the four processes of mechanical refrigeration cycle?
A refrigeration cycle has four major components: the compressor, condenser, expansion device, and evaporator. Refrigerant remains piped between these four components in the refrigerant loop.
How does the first law of thermodynamics apply to refrigerators?
This law has more to do with modern refrigerators because it defines that it is possible to raise the temperature of a system either by adding heat (thermal energy) or by doing work on it.
What are the three laws of refrigeration?
Refrigeration lawsHeat causes refrigeration in vapor absorption refrigeration. ... On decrease of pressure, the boiling temperature decreases. ... Heat naturally flows higher temperature to low temperature. ... Clausius statement of second Law of Thermodynamics.More items...•
What is mechanical refrigeration?
Definition of mechanical refrigeration : the abstraction of heat by means of a working substance subjected to refrigerating thermodynamic cycles in which the energy is supplied by a mechanical compressor : cooling produced by a machine instead of by melting ice.
Which type of refrigeration system used mechanical energy?
Mechanical-Compression Refrigeration Systems Mechanical compression is used in commercial and industrial refrigeration, as well as air conditioning. Most HVAC companies install this type of cooling system.
What are the 4 main components of a refrigeration system?
The 4 Main Refrigeration Cycle ComponentsThe compressor.The condenser.The expansion device.The evaporator.
Which law of thermodynamics does a cooling system apply?
The second law of thermodynamics describes the direction in which physical phenomena can occur. One statement of the second law is: Heat can flow spontaneously from hot to cold but never from cold to hot.
What is the first law of thermodynamics for air conditioner?
The refrigerant enters the coil as a liquid, and warm air passes over that coil. The refrigerant absorbs heat and removes it from the air, raising the refrigerant's temperature to the boiling point in the process.
Which equipment works on Zeroth Law of Thermodynamics?
ThermometersThermometers. The zeroth law of thermodynamics defines temperature and makes thermometers possible. For a thermometer to be useful, though, it must be first calibrated.
Is entropy The second law of thermodynamics?
The Second Law of Thermodynamics states that the state of entropy of the entire universe, as an isolated system, will always increase over time. The second law also states that the changes in the entropy in the universe can never be negative.
What is the process of refrigerant?
In the process of refrigeration, the available heat, with the system to be maintained at low temperature, is continuously removed and transferred to the surrounding which is at high temperature.
How does refrigerant change its properties?
The refrigerant has specific properties. It evaporates at low temperature and pressure by absorbing heat from the system to be cooled and condenses at high temperature and pressure rejecting heat to the atmosphere.
Why does ammonia evaporate at low temperature?
Thus, liquid ammonia is evaporated at low temperature because of the low partial pressure available for ammonia in evaporator. In condenser, the condensation of ammonia takes place at high temperature where no hydrogen is present and the heat is rejected to the atmosphere.
What is the process of removing heat continuously from the system to be cooled to maintain the temperature lower than the atmospheric?
Refrigeration is the process of removing heat continuously from the system to be cooled to maintain the temperature lower than the atmospheric temperature.
Why does a refrigerator need external power?
Hence, a refrigerator needs external power for removing heat continuously from the cabinet to maintain temperature lower than the surrounding.
How many kJ/min is 1 ton of refrigeration?
The capacity of a refrigeration system is expressed in terms of tons of refrigeration. In SI system, 1 ton of refrigeration = 210 kJ/ min = 3.5 kW
Is ammonia bad for refrigerators?
The main use of this system has been in household refrigerators. Even though ammonia is toxic, it became popular due to its simplicity. The chance of leakage is minimum and also the quantity of ammonia is so small that there is little danger.
How does the refrigeration cycle work?
The refrigeration cycle is based on the long known physical principle that a liquid expanding into a gas extracts heat from the surrounding substance or area. (You can test this principle by simply wetting your finger and holding it up. It immediately begins to feel cooler than the others, particularly if exposed to some air movement. That's because the liquid in which you dipped it is evaporating, and as it does, it extracts heat from the skin of the finger and air around it).
What is a chiller in refrigeration?
The Principles of Basic Refrigeration. A chiller is simply a device that used to remove heat from something. For industrial purposes, chillers can be thought of as a component within a complex mechanical system that is used to remove heat from a process or substance.
How does a compressor transfer heat from a refrigerant to a condenser?
Now this low-pressure, low-temperature vapor is drawn to the compressor where it is compressed into a high-temperature, high-pressure vapor. The compressor discharges it to the condenser, so that it can give up the heat that it picked up in the evaporator. The refrigerant vapor is at a higher temperature than the air passing across the condenser (air-cooled type); or water passing through the condenser (water-cooled type); therefore that is transferred from the warmer refrigerant vapor to the cooler air or water.
How does heat travel from the evaporator to the evaporator?
Heat will travel from the warmer substance to the evaporator cooled by the evaporation of the refrigerant within the system , causing the refrigerant to "boil" and evaporate, changing it to a vapor. This is similar to the change that occurs when a pail of water is boiled on the stove and the water changes to steam, except that the refrigerant boils at a much lower temperature.
What is the chemical compound that is compressed and condensed into a liquid and then permitted to expand into a?
E). Refrigerants, are chemical compounds that are alternately compressed and condensed into a liquid and then permitted to expand into a vapor or gas as they are pumped through the mechanical refrigeration system to cycle.
What is the temperature of a cold?
Another definition describes it as the absence of heat, no process yet has been devised of achieving "absolute zero," the state in which all heat has been removed from any object, substance, or area. Theoretically this zero point would be 459.69 degrees below zero on the Fahrenheit thermometer scale, or 273.16 degrees below zero on the Celsius thermometer scale.
How to find change in heat in BTU?
Where Change in heat (in Btu) = Weight (in pounds) x Temperature Difference.
Read Other Posts
Commercial refrigerators are the essential appliances and tools of many retail stores and restaurants, for a variety of different stored products that are ...
Customizing & Branding
Nenwell provides you with the custom & branding solutions to make the perfect refrigerators for different commercial applications and requirements.
Who Should Attend?
Others interested in understanding the basic principles and practices of mechanical integrity for industrial refrigeration systems
Additional Information
This course is part of the Process Safety Management Professional Certificate. Increase your knowledge and effectiveness at managing PSM/RMP programs for your ammonia refrigerated facility, while earning a recognized credential. Course can be taken individually as well.
Create a custom learning experience
We can deliver this course as an on-site learning experience tailored to your organization’s specific training needs.
How does a refrigerator work?
In other words, refrigeration is a reverse operation of a heat engine. A heat engine takes heat from a hot body, converts a part of it into mechanical work, and rejects the rest to a colder environment. On the contrary, a refrigerator employs mechanical work to transfer heat from a region with a lower temperature to a region with a higher temperature. This periodic delivery of heat is known as the refrigeration cycle or the vapor-compression refrigeration cycle. Let’s discuss how this process is carried out inside a refrigerator.
What is the refrigeration cycle?
Refrigeration Cycle. In this cycle, a volatile refrigerant fluid is pumped through the cooling coils of the evaporator to the indoor compartment of a refrigerator. Inside these coils, the refrigerant evaporates due to the latent heat provided by the food items.
Why is a condenser called a condenser?
It is called a condenser because the removal of heat is achieved by the condensation of the refrigerant fluid from vapor to liquid state inside the condensing coils. Heat is given off as temperature drops to the condensation temperature.
What is the purpose of a condenser in a refrigerator?
A condenser, or condensing coils, is a mesh of pipes that one can find on the backside of the refrigerator. The main function of the condenser is to remove the inner heat of the refrigerator, just like a radiator. It is called a condenser because the removal of heat is achieved by the condensation of the refrigerant fluid from vapor to liquid state inside the condensing coils. Heat is given off as temperature drops to the condensation temperature.
How does a compressor affect the temperature of a refrigerator?
In refrigerators, the compressor mechanically increases the temperature of the refrigerant fluid by forcing it to move through a low-volume pipe. The refrigerant fluid enters the compressor as a low-pressure and low-temperature gas, and then it leaves the compressor as a high-pressure and high-temperature gas.
How does a thermostatic expansion valve work?
A thermostatic expansion valve acts as a regulator that controls the flow of the liquid refrigerant into the evaporator. A thermostat (a regulating device component that senses the temperature and gives an output accordingly) controls the cooling process by switching the compressor on and off. When the sensor senses that it’s cold enough inside a refrigerator, it turns off the compressor. If it senses too much heat, it switches the compressor on and begins the cooling process again. This is the reason why we hear a humming sound at regular intervals coming from the refrigerator.
What is the function of the evaporation coil in a refrigerator?
The evaporation coils are present inside the refrigerator where we put our food items. The refrigerant fluid is let into these coils by the thermostatic expansion valve.