Archive for the ‘Mechanical Engineering’ Category

INTRODUCTION

National energy security, rising energy prices, increasingly competitive global markets, and stringent regulations for environmental emissions are the primary driving forces in the search for sustainable and economically viable technologies that incorporate efficient and clean approaches to energy conversion and utilization.  Internal combustion (IC) engines are the prime movers of choice when high power densities and efficiencies are desirable.  Because of relatively cheap fuel prices in the last few decades, IC engines had been optimized for high power densities and low emissions.  However, in recent years, with escalating fuel prices and concerns about sustainability, engine efficiency has assumed greater importance.  Read More »

Power boilers consist basically of a steam generator, a steam turbine–driven generator for electric power generation, and a turbine effluent steam condenser, which in most cases is cooled by water.

The purpose of this study is to determine whether air instead of water cooling of a coal-fired boiler steam condenser is a desirable option in cases in which the boiler must be sited remote from its source of fuel. For a coal-fired power plant, for example, it is not uncommon to locate the plant a considerable distance from the coal mine and transport the coal by rail to the plant. This may be necessary to obtain an acceptable supply of water that is suited to the needs of the boiler, for steam production, and for condensation of the steam turbine effluent. Read More »

Introduction

As the supply of fossil fuels decreases, it is possible that future stationary or mobile energy systems will use hydrogen fuel cells. This article outlines some rules of thumb for fuel cells and describes the basic calculations required to size a fuel cell appropriately and determine hydrogen fuel requirements. Read More »

INTRODUCTION

The term CCHP (combined cooling, heating, and power) is used to describe all electrical power generation systems that utilize recoverable waste heat for space heating, cooling, and domestic hot water purposes.  The main difference between CCHP systems and the typical methods of electrical generation is the utilization of the waste heat rejected from the prime mover to satisfy the thermal demand of a facility. Read More »

Problem Description

This article describes the performance of a novel vertical axis wind turbine (VAWT). The Zephyr VAWT has a patented stator cage that can increase the turbine’s performance through the creation of low-pressure vortices. The patented features of the turbine allow it to perform in both low-wind and high-turbulence conditions; however, a relatively low maximum efficiency is exhibited by the current prototype design. A problem arises when incoming air is diverted away from the convex sides of the rotors, reducing opposing forces to the direction of rotation; however, the solidity (blockage) is increased, reducing the overall flow through the turbine. Read More »

Introduction and Problem Statement

Process heating systems are some of the largest energy-intensive systems in most industrial facilities and account for approximately 36% of industrial energy consumption.  These systems may include equipment such as furnaces, ovens, heaters, kilns, and lehrs.  They are used in a variety of processes in an industrial energy system to transfer heat from energy sources to the products.  Read More »

INTRODUCTION TO ELECTROSTATIC PRECIPITATORS

Electrostatic precipitators (ESPs) are the most commonly used, effective, and reliable particulate control devices; they are employed mostly in power plants and other process industries. The particle-laden flue gas from the boiler flows through the ESP before it enters the environment. The ESP works as a cleaning device, using electrical forces to separate the dust particles from the flue gas. A typical ESP consists of an inlet diffuser known as an inlet evase, a rectangular collection chamber, and an outlet convergent duct known as an outlet evase. Perforated plates are placed inside the inlet and the outlet evase for the purpose of flow distribution. Inside the collection chamber there are a number of discharge electrodes (DEs) and collection electrodes (CEs). A set of discharge electrodes is suspended vertically between two collection electrodes in a typical wire-plate ESP channel. While the flue gas flows through the collection area, electrostatic precipitators accomplish particle separation through the use of an electric field in the following three steps. The electrical field does the following: Read More »

Introduction
Stationary gas turbines are used in a wide range of applications, including peaking power facilities, emergency backup power systems (e.g., nuclear plants), and cogeneration plants. They also are used widely in the oil and gas industry to provide power in remote locations, such as offshore and onshore production facilities. Read More »