Table of Contents

Seminar On Absorption Refrigeration System PDF Report Download

ABSTRACT

This work presents an experimental study of an ammonia – water absorption refrigeration system using the exhaust of an internal combustion engine as energy source. The exhaust gas energy availability and the impact of the absorption refrigeration system on engine performance, exhaust emissions, and power economy are evaluated. A production automotive engine was tested in a bench test dynamometer, with the absorption refrigeration system adapted to the exhaust pipe. The engine was tested for 25%, 50%, 75% and wide-open throttle valve. The refrigerator reached a steady state temperature between 4 and 13 degree centigrade about 3 hours after system start up, depending on engine throttle valve opening. The calculated exhaust gas energy availability suggests the cooling capacity can be highly improved for a dedicated system. Exhaust hydrocarbon emissions were higher when the refrigeration system was installed in the engine exhaust, but carbon monoxide emissions were reduced, while carbon dioxide concentration remained practically unaltered.

INTRODUCTION

Energy efficiency has been a major topic of discussions on natural resources preservation and costs reduction. Based on estimates of energy resources reduction at medium and long terms, it is vital to develop more efficient processes from energy and exergy standpoints. Environment preservation must also be considered through energy optimization studies. An important point to mention absorption refrigeration systems is the continuing substitution of chlorinated fluorocarbons (CFCs) by alternative refrigerants, according to the Montreal Protocol, signed in 1987 by 46 countries and revised in 1990 to protect the ozone layer. Other motivating factors are the continuous optimization of the performance of internal combustion engines and the increasing utilization of air conditioning in vehicles, as it reaches the
status of essential need for modern life. Internal combustion engines are potential energy sources for absorption refrigeration systems, as about one third of the energy availability in the combustion process is wasted through the exhaust gas. Thus, use of the exhaust gas in an
absorption refrigeration system can increase the overall system efficiency.
This work has as an objective the study of the feasibility and potential of using the internal combustion engine exhaust gas as energy source for an absorption refrigeration system. For this purpose was performed an experimental study on a commercial 215-l refrigerator. The
impact of the absorption refrigeration system on engine power output and exhaust emissions is analyzed, in order to know how this system influences the operation of an internal combustion engine.

OBJECTIVE

The demand for fossil fuels is on the rise and the threats possessed by the pollutants cannot be neglected. And so is the requirement for energy efficient machines and this topic deals with the usage of „wasteful‟ energy from vehicular exhaust e missions for refrigeration or air
conditioning purpose.
Air conditioning is also becoming a necessity in our society. Considering this, usage of different methods like absorption refrigeration systems, adsorption systems, solar systems, can contribute to the overall efficiency of vehicles.
The topic also deals with an experiment related to a vehicle integrated with absorption refrigeration system. Its results and the scopes are also discussed in the topic.

Fig. 1 shows a schematic of the basic ammonia – water absorption refrigeration cycle. High pressure ammonia vapor enters the condenser, where it transfers heat to the neighborhood. Liquid ammonia leaves the condenser and passes through an expansion valve, reaching the evaporator pressure. The refrigerant then enters the evaporator, where it receives heat from the cold source, turning into low pressure vapor. In the sequence, ammonia vapor enters the absorber, where a weak solution of water and low concentration ammonia absorbs the refrigerant and, at the same time, transfers heat to the neighborhood. The solution has now a high ammonia concentration, and is pumped to the vapor generator, where it receives heat from an external source. The ammonia in the solution then evaporates, separating from water and flowing to the condenser to start a new cycle. A weak water – ammonia solution leaves the vapor generator and enters the absorber to absorb ammonia vapor from the evaporator. A heat exchanger between the absorber and the vapor generator transfers heat from the weak solution leaving the vapor generator to the high ammonia concentration solution going into the vapor generator.

CONCLUSION

The engine exhaust gas was confirmed as a potential power source for absorption refrigeration systems.
The domestic absorption refrigerator tested showed low coefficient of performance and did not provide the cooling capacity needed for automotive application. However, a dedicated absorption refrigeration system may be able to take advantage of the exhaust gas power availability and provide the cooling capacity required for automotive air conditioning.
Introduction of the absorption refrigeration system in the engine exhaust system did not cause significant pressure drop in the exhaust flow, as the engine output power was increased and specific fuel consumption was decreased with removal of other exhaust system components.
Overall, carbon monoxide emission was decreased when the absorption refrigerator was installed in the exhaust gas, while hydrocarbon emissions showed an increase. Changes in exhaust components concentration were a consequence of the major modifications in the exhaust system.