Fig 2.1 Content of this post 
Introduction to non-conventional refrigeration method
The Non-conventional refrigeration system works on the principle same as vapor compression refrigeration system. Instead of compressor & condenser it uses different kind of setup. In simple vapor compression system we use refrigerant for getting refrigerating effect.
In this post we have to see following types of refrigerating system :
1. Vortex tube
2. Pulse tube refrigeration
3. Solar refrigeration 

1. Vortex Refrigeration System
Fig 2.2 Vortex tube Refrigeration 
Construction:
It is one of famous method of non conventional method of refrigeration. Schematic diagram of vortex tube refrigeration system is shown below.
It consists of nozzle, diaphragm, valve, hot-air side, cold-air side. Nozzles are converging, diverging or converging type as per design. Nozzle is with higher velocity , high mass flow rate and minimum loss. High velocity air enter at the tube through nozzle and move forward(in fig right side of nozzle)spirally to the hot side. There is arrangement made for creating higher velocity at the entry of nozzle.
Hot side is of circular cross section and there is valve which obstruct the flow of hot air and move centrally backward and reach towards the cold side through diaphragm hole.Diaphragm is a cylindrical piece of small thickness and having a small hole of specific diameter at the center.

Working :
When compressed air passes through nozzle or spiral groove ,expansion of compressed air takes place.During the expansion process, its pressure decreases while velocity increases. 
This air flows in the forward direction spirally, when it reaches at wall there is restriction to this air, due to this there is increase in pressure and air flows reversely at the center. 
There is heat transfer between forward air and reversed air steam, the result obtained is cold air obtained on opposite side of wall, while hot air obtain on wall side. 
Number of experiments are carried out on vortex tube by Prof. Parulekar in IIT Mumbai, but no one can describe actually theory behind it. 

Application:
1. It can be used (cold air) as the cooler for machining process.
2. It can be used for cooling of suits.
3. It can be used for air conditioning purpose.
4. At the same time cold air can be used for cooling purpose hot air can be used for heating purpose.

Advantage :
1. simple construction
2. No moving part.
3. Cost is low.

2. Pulse tube refrigeration
Fig 2.3 Pulse tube Refrigeration 
Construction:
Pulse tube is simple but facilitating method of obtaining lower temperature & the problem of lubrication at the low temperature and the problem of lubrication at the low temperature is basically eliminated as moving parts are absent. 
Pulse tube refrigerant first reported in 1961 by Gifford. It consist of following parts : 
1. Pulse tube
2. Regenerator
3. Valve mechanism
4. Vacuum system
5. Cooling system
The regenerator is main component of improving performance of pulse tube refrigerator. it is made up of bronze wire mesh. 
The cooling capacity of regenerator is very small, high quality thermal insulation is necessary. Convection and Radiation losses are reduced by keeping entire pulse tube along with regenerator in vacuum container. 

Working:
It Consist of two processes:
1. Pressure buildup and heat rejection:
In this process valve admits high pressure gas through regenerator where air is cool. Then the gas enters the tube where act as gas piston . The gas piston compresses the gas which already present in the tube. Temperature of tube gas increases and it rejects heat to cooling media water. 
2. Pressure realizing and heat absorption:
The admitted gas in the first process is now connected to exhaust with the help of valve mechanism, hence gas exhausted by realizing pressure.Now expansion of tube gas take place and the lower temperature obtained at the cold end. 
When helium gas works as media at 25 Kg/cm2, Gifford reported temperature at cold end is 124 K. for single stage pulse tube and 79 K at cold end for two stage pulse tube. 
In IIT Prof. Parulekar & Prof. Narayankar uses air as media and reported lower temperature 214 K. 
The performance of pulse tube depend on 
a) Pulse Rate 
b)Ratio of hot end length to total length of tube. 
c) Temperature at cold end. 

3.Solar Refrigeration system
Fig 2.3 Solar Refrigeration System
Figure shows Solar refrigeration system as name indicate refrigeration effect obtained by Solar radiation energy. It consist of two system first is Solar collected system and another vapor compression system as above. 
In this system vapor compression system is used that is compressor => Condenser => Expansion =>Evaporator. We discuss VCC(vapor compression system)is deep another blog . 
To run the compressor steam turbine is used to generate pressurized super-heated steam, boiler is used. 
To generate such type of steam parabolic collector is used. Parabolic collector collect all energy from sun and steam generated and turbine run on boiler steam. 
Turbine and Compressor run on turbine and VCC system works and refrigeration effect obtained in Evaporator and used for application. 
There are different other types of non conventional methods but this three main types.