Refrigeration System based on Vapour Absorption Cycle having Solar Powered Generator for Domestic Use

Our project is based on vapour absorption cycle for refrigeration. It uses heat to produce high pressure vapour of refrigerant rather than a compressor which consumes electricity. In vapour compression refrigeration system, a major portion of the provided electricity is

Project Title

Refrigeration System based on Vapour Absorption Cycle having Solar Powered Generator for Domestic Use

Project Area of Specialization

Mechanical Engineering

Project Summary

Our project is based on vapour absorption cycle for refrigeration. It uses heat to produce high pressure vapour of refrigerant rather than a compressor which consumes electricity. In vapour compression refrigeration system, a major portion of the provided electricity is consumed by a compressor. But vapour absorption uses heat energy, which is low grade energy. Solar energy is used to provide the required heat to our cycle.
We are designing the refrigeration system for the cooling capacity of 1 ton. The working pair for our system is Lithium bromide-water solution where water is refrigerant and lithium bromide is adsorber. For the cooling capacity of 1 ton, our system requires 4.46kW of heat. This heat is provided by a parabolic dish solar collector of 2.5-meter diameter.

Project Objectives

Pakistan is an energy deficient country and this deficiency hits its peak in summers when everyone is using air conditioners powered by electricity. The main objective of our project is to use an alternative method, other than electricity, to do refrigeration. This will solve the problem of load shedding.
Moreover, the world is running out of non-renewable resources and sooner or later we must shift towards renewable energy. Sun is one of the best ways to harness renewable energy. Since our refrigeration system requires heat to operate, solar heat energy is used as a power source for our system. Our system will have negligible running costs in summer at daytime, so our project will reduce the electricity bills of consumers.

Project Implementation Method

Since we are designing our system for commercial application in schools and offices, the working hours are 0900 to 1700 hours. The solar flux remains above 0.8kW/m2 throughout this time period (for which our project is designed for). So, we can easily use this project for such applications.
During the night our system uses natural gas as a heating source. We have calculated that if PEL ACE air conditioner, capacity of 1-ton,  is used 12 hours a day, the electricity bill will increase roughly by Rs. 9500. But if our project is working 12 hours on gas, it's running cost will be Rs. 3397/month. This clearly shows the cost effectiveness of our system continuously working on solar heat in the daytime and on natural gas during the night.
Another question may arise regarding the size of our project. The size of our project is similar to the compressor unit of a split air conditioner. The exact dimensions of our system are (100cm x 40cm x 90cm) with the dish of 2.5-meter diameter on the top of the building.

With the slight modification and directing the heated water towards the inner unit, the system can be used to heat the building in winters.

Benefits of the Project

• An absorption chiller is working on solar energy. As it is a renewable energy source so our system is sustainable. This also helps in  reducing the cost of electricity since the compressor is not used in vapour absorption systems. An average 1 ton vapour compression air conditioner with working of 12 hours a day has a running cost of approximately Rs 9500 monthly. While our system is free of cost during the daytime. While working at night, it costs Rs 3397 monthly. It is a one-time investment with a life cycle of around 10-15 years.
• Due to lack of compressors in the machine, noise and vibration are significantly reduced in the building, providing a quiet environment with high reliability.
• The refrigerants primarily used in absorption chillers do not contribute to global warming and ozone depletion. In our system, water is used as a refrigerant which is non-hazardous and non-toxic.
• We are using parabolic dish collector for directly giving heat energy to our generator as it has high efficiency, about 78-89%, of converting solar energy into heat energy.

Technical Details of Final Deliverable

Our refrigeration system is based on vapour absorption cycle. We are designing and fabricating the system for 1 ton cooling. In this cycle, heat is used to boil the refrigerant-absorber solution which gives high pressure vapours. The main components of our system are condenser, expansion valve, evaporator, absorber and desorber/generator.  While the working pair for our system in lithium bromide-water. Where water is refrigerant and lithium bromide is adsorber.

The refrigerant vapours from the evaporator get absorbed in the absorber and pumped towards desorber. In the generator, heat is provided to boil the water vapours from the solution. These water vapours are condensed in the condenser and then throttled in the evaporator for cooling. Additional heat exchanger is present between rich (in lithium bromide) solution coming from generator towards absorber and weak (in lithium bromide) solution coming from absorber towards generator to increase the efficiency of the system. The working pressure of generator and condenser is 7.3kPa while working pressure of absorber and evaporator is 1.23kPa. These pressures are well below atmospheric pressure, which is 101kPa. So we needed to design and fabricate two vacuum vessels for our system. ASME Section 8, division 1 was used to find the required vessels.
4.46kW heat is required in the generator for cooling capacity of 1 ton. This heat is provided by a parabolic dish solar collector of size 2.5 meters in diameter.

Final Deliverable of the Project

Hardware System

Core Industry

Energy

Other Industries

Core Technology

Others

Other Technologies

Sustainable Development Goals

Good Health and Well-Being for People, Affordable and Clean Energy

Required Resources

If you need this project, please contact me on contact@adikhanofficial.com