EXPERIMENTAL DESIGN AND CONSTRUCTION OF A PROTOTYPE SOLAR POWERED INTERMITTENT ABSORPTION VAPOR REFRIGERATOR
At present, non-renewable energy sources are depleted constantly, Harmful emissions from fossil fuels and chlorine-based refrigerants have led to economic and more severely, environmental hazards. The world has been working to reduce hazardous emissions while developing renewable energy sources and technology. Leading the industry of renewable energy is solar power. By collecting and storing solar heat, and transferring this energy to power an absorption refrigerator, energy efficiency can improve, eradicating usually necessary (poor and sometimes unavailable) electricity.
The development of an inexpensive, modular, small-scale cold room based upon the absorption refrigeration process. This project was developed to proffer means of providing refrigeration to agricultural products in communities lacking or unable to afford conventional energy sources (electrical energy).
A solar-driven ammonia absorption refrigeration system was designed, a modular prototype constructed and tested. It was an intermittent system where ammonia and water were used as refrigerant and absorbent respectively. The main components like evaporator, condenser, and generator were designed based on certain assumptions such as generator temperature 70oc, refrigerating effect of 5 tonnes (for full-scale construction). The necessary heat and mass transfer equations describing the working properties were specified. The theoretical obtained COP was 0.25. Information on designing the condenser, evaporator, and generator of the unit has been presented.
It was assumed that the vapor generating from the generator was 100% pure ammonia vapor. The thermal energy input was calculated to be with Is (solar intensity) = 600 W/m2 where collector efficiency was assumed 30% and collector mirror surface area was 2.3m2, but for purpose of increasing the efficiency, it was the collector area was increased by 20%.
TABLE OF CONTENTS
CERTIFICATION 2DEDICATION 3ACKNOWLEDGEMENT 4ABSTRACT 5CHAPTER ONE 7INTRODUCTION 91.1 Background of Study 91.2 Statement of the Problem 91.3 Aims of the project 101.4 Objectives 101.5 Methodology to be adopted 101.7 Project Scope 112.1 Historical background of refrigeration 122.1 Theoretical background solar refrigerator 122.1.1 Indices of Performance 122.1.2 Operation of the Intermittent Ammonia-calcium chloride System 132.1.3 Analysis of the Ideal Cycle 132.3 Absorption method 192.4 Working principle of vapor adsorption methods 202.5 Solar energy 242.5.1 Methods of generation 262.6 Review of the common structure of cold room 272.6 Working Fluid for the Absorption Refrigeration Systems 283.1 Materials and material selection 30Design configuration 303.2 Design Conditions for prototype model 31Condenser design consideration 33Heat rejection in the condenser 33Evaporator design consideration 343.3 EXPERIMENTAL SETUP (PROTOTYPE) 373.4 Experimental procedure (Prototype) 38CHAPTER 4 40RESULT AND DISCUSSION 404.1 EXPERIMENTAL RESULT 404.2 BILLS OF ENGINEERING MEASUREMENTS AND EVALUATION (BEME) 434.3 DISCUSSION 43Chapter 5 45CONCLUSIONS AND RECOMMENDATION 455.1 CONCLUSIONS AND RECOMMENDATION 45
CHAPTER ONEINTRODUCTION1.1 Background of the Study
Refrigeration is the process of removing heat from a substance under controlled conditions (Muthu et al 1999). Refrigeration uses the evaporation of a liquid to absorb heat. Before mechanical refrigeration systems were introduced, people cooled their food with ice and snow, either found locally or brought down from the mountains. The first cellars were holes dug into the ground and lined with wood or straw and packed with snow and ice. This was the only means of refrigeration for most of history.Moreover, approximately 62 million mew units are being manufactured worldwide every year, and hundreds of millions are currently in. use. (UNEP, 1995) it is anticipated that the production of refrigerator-freezers will substantially increase in the near future as a result ofthe increased demand, especially in developing countries. Therefore, in response to global concerns over greenhouse resorts are being made to produce refrigerator-freezers with low energy consumption.This project will result in the development of a system that can be a decisive step in bringing refrigeration to the far-off rural areas. This project shall focus on the design of an intermittent absorption refrigeration system; the prototype model will be constructed and tested to observe its functionality.
1.2 Statement of the ProblemLocal food systems can contribute to socially, economically, and ecologically beneficial food production for local communities. In order to deliver quality products to the consumer, local food systems must utilize rapid cooling and cold storage technology. In the past thirty years, the number of local farms increased 11.2% thus the need for energy-efficient cold storage units (USDA, 2013). Cold storage is essential for vegetable farmers to preserve product quality and extend the revenue period. A personal survey conducted in the oil-rich Niger Delta region that is also blessed naturally with the sources of agricultural products reveals that no development such as reliable solar-powered cold storage has been found in the area whereas the level of food crops production and commercial fishing in the community demand that at least one should be provided. The necessity primarily prompted the essentiality of this study.The studies will also point out that the principle of refrigeration as studied in the classroom would not only remain in theory but can be made tangible in typical practical application in order to be fully, faithfully, and amply appreciated.
1.3 Aims of the projectThe aim of this project work is to experimentally design and construct a working prototype model of a solar-powered intermittent vapor absorption refrigerator.
1.4 Objectives⦁ To calculate solar energy and system power requirements⦁ To construct and test a workable prototype⦁ To use this project to gain substantial knowledge in solar energy generation and absorption refrigeration cycle.1.5 Methodology to be adoptedTo arrive at a successful design and construction, the algorithm below will guide us on the steps to follow:ImageFigure 1.6.1 Research/literature review A literature review will be carried out on the existing experimental studies; solar generation methodology will be studied.
1.6.2Design calculationsDesign considerations such as solar intensity, power requirement, material heat conductivity, heat rejected, energy balance, etc.
1.6.3MaterialsselectionAppropriate materials will be selected bearing in mind the following objectives⦁ Low cost⦁ Availability to local manufacturers⦁ Less weight⦁ Heat lagging properties.
1.6.4 CAD model and thermal analysisSolid Works engineering software will be used to produce a CAD model of the design and thermodynamic analysis will be done to give a better understanding of the design.
1.6.5 materials acquisitionMaterial for the construction will be locally sorted for, the evaporator; condenser, etc. will be acquired in the local market.
1.6.6 constructionFinally, a workable prototype will be fabricated on a reduced scale to experimentally represent the solar-powered VAR system.
1.7 Project ScopeThe scope of this project is limited to design calculation, material selection, CAD model, and fabrication of a working prototype. The prototype to be constructed will use an alternative heat emitting body to represent the sun (solar), where the is no good weather during testing..