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Sorption cooling systems have been used commercially for some decades for different applications including air conditioning and refrigeration, using a diverse range of thermodynamic cycles and technologies for many size and capacities. However, their use has been limited mainly because of their low efficiency and high investment costs, at least compared with compression systems that are widely used...
The knowledge of the basic principles of thermodynamics allows us to understand the conditions and necessary limitations in order to transform heat in work, transferring heat from a thermal source of high temperature to a smaller one. Thermal machines work under this principle, however, there are machines that consume work (external) and produce heat, that is to say in the inverse sense of a thermal...
From Chapter 1 it is clear that nowadays electricity and cooling demands are growing considerably worldwide, and that also there is a necessity to provide these by using more efficient and cleaner technologies, as the proposed in the present book. A profitability assessment is determinant to decide the implementation and use of some technologies; because of this in the present chapter, an economic...
As already discussed in Chapter 1, energy is a finite resource and its rational use implies an increase in energy efficiency. The electric generation efficiency is always less than 100% due to resistive, transmission and distribution losses, which can be quantified as heat sent to the environment. This waste heat determines the quantity of energy that can be used by other systems in order to improve...
The word energy is derived from the Greek in (in) and ergon (work). The accepted scientific energy concept has been used to reveal the common characteristics in diverse processes where a particular type of work is produced. At the most basic level, the diversity in energy forms can be limited to four: kinetics, gravitational, electric, and nuclear. Energy is susceptible to being transformed...
In this chapter the basic thermodynamic and electrochemical principles behind fuel cell operation and technology are described. The basic electrochemistry principles determining the operation of the fuel cell, the kinetics of redox reactions during the fuel cell operation, the mass and energy transport in a fuel cell, etc., are described briefly to give an understanding of practical fuel cell systems...
Before going into the details of cogeneration combined heat and power (CHP) processes, it is necessary to establish the operation principles and performance characteristics of the most common fuel cells for consideration in CHP processes. According to the phenomena governing the performance of fuel cells, it is worth noting that fuel cells are electrochemical energy conversion devices, where redox...
Fuel cells are devices where electrical energy is produced by redox electrochemical reactions of hydrogen or enriched hydrogen fuels and oxygen, or simply air. Powerful fuel cells or stacks have emerged as potential replacements for the internal combustion engine in automobile vehicles, because the use of fuel cells implies clean and efficient use of energy, and the unique by-products are water and...
Although conventional cogeneration systems have been used successfully in the last two decades, most of them have been large units using mainly hydrocarbon fuels that are becoming increasingly expensive. New cogeneration systems based on fuel cells and sorption air conditioning systems promise to be an energy-saving alternative for situations when cooling, heating and power are needed at low and...
In this work, a computer simulation program was developed to determine the optimum operating conditions of an air conditioning system during the co-generation process. A 1kW PEMFC was considered in this study with a chemical/electrical theoretical efficiency of 40% and a thermal efficiency of 30% applying an electrical load of 100%. A refrigeration-absorption cycle (RAC) operating with monomethylamine–water...
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