Section 1. Introduction

This document has been prepared by the Water Technology Subcommittee of the ASME Research and Technology Committee on Steam and Water in Thermal Systems as a consensus of proper current operating practices for the control of feedwater and boiler water chemistry in the operation of industrial and institutional, high duty, primary fuel fired boilers. These practices are aimed at minimizing corrosion, deposition, cleaning requirements, and unscheduled outages in the steam generators and associated condensate, feedwater and steam systems for boilers, and steam system components which are currently available. This publication is an expansion and revision of the operating practice consensus documents previously issued by the Committee [1-3]. The tabulated values herein update and replace the ones previously published. Titles have been edited and clarified. The text has been reordered and modified where necessary. THE TEXT IS OF PRIME IMPORTANCE AND SHOULD BE CONSIDERED FULLY BEFORE USING THE TABULATED VALUES. One Appendix has been added to provide additional guidance.

Consensus on Operating Practices for the Control of Feedwater and Boiler Water Chemistry in Industrial and Institutional Boilers

The Water Technology Subcommittee of the ASME Research and Technology Committee on Water and Steam in Thermal Systems, under the leadership of Mr. Robert D. Bartholomew has revised the Consensus on Operating Practices for the Control of Feedwater Boiler Water Chemistry in Modern Industrial Boilers, first published in 1979 with prior revisions published in 1994 and 1998. The task group consisted of a cross section of manufacturers, operators, chemical treatment contractors and consultants involved in the fabrication and operation of industrial and institutional boilers. Members of this group are listed in the acknowledgments. This current document is an expansion and revision of the original, with reordered and modified texts where considered necessary. While significant revisions have been incorporated, it is recognized that there are areas of operating practice not addressed herein. Additional information is available from the references. It is the plan of the ASME Research Committee to continue to review this information, and revise and reissue this document as necessary to comply with advances in boiler design and water conditioning technology.

Introduction of a novel electric field-based plate heat sink for heat transfer enhancement of thermal systems

Purpose The purpose of this study is to use an electric field technique to design novel heat sinks capable of rejecting as much heat as possible in a limited space. Configuration of electrodes in this study can be used for increasing the efficiency of heat sinks. Design/methodology/approach This study investigates a novel electrohydrodynamic (EHD)-based heat sink for thermal management of electronic devices and thermal systems. The significant part of designing an EHD heat sink is the arrangement of the electrodes. A numerical simulation is performed for a heat sink with two parallel plates to determine the optimum dimensional configuration of electrodes. The upper plate of this heat sink is the ground electrode with a constant atmosphere temperature, and the lower plate of it with flush-mounted high-voltage electrodes has uniform heat flux. Findings The results show that heat transfer changes by the size of the vortices and the number of them. These vortices are emerged by the electric field, and the number of them increases with increasing the number of electrodes. The interaction of vortices size and number leads to having the lowest average temperature in the optimum case by two high voltage electrodes with widths of 7.5 mm and a 17.5 mm gap between them. In comparison with the case without the electric field, with increasing the applied voltage to 30 kV, the efficiency of this EHD heat sink increases up to 37%. Originality/value Improvements in electrical equipment make them more compact with higher heat fluxes. Hence, the amount of heat to be dissipated per area increases and needs thermal management to operate at their design temperatures. Therefore, to improve the performance and life span of electronic components and increase their efficiency, it is necessary to design heat sinks to decrease their maximum (peak) temperature.

Optical Raytracing Analysis of a Scheffler Type Concentrator

The Scheffler type concentrator is a curved metal reflector particularly suitable for solar thermal systems with a receiver fixed to the ground. Its operating principle is to deform the reflector throughout the year to optimize its performance in collecting sunlight. This study analyses the optical performance of a Scheffler reflector during the year. A CAD software tool is utilized to reproduce the mechanical deformations of a real Scheffler concentrator and the shape of the light spot on the receiver is analyzed by means of raytracing simulations. The starting configuration is the equinoctial paraboloid, which produces a point-like spot on the two equinox days only. On all other days of the year, this paraboloid is deformed in a suitable way in order to keep the spot as small as possible, but, even so, it is no longer a point-like spot. In the present work the simulated light distributions on the receiver, generated by the paraboloids (deformed or original), are compared. The results confirm the working principle of the Scheffler type concentrator and allow correctly sizing the receiver.