As a major utility system in industry, boilers consume a large portion of the total energy and costs. Significant reduction of boiler cost operation can be gained through improvements in efficiency. In accomplishing such a goal, an adequate dynamic model that comprehensively reflects boiler characteristics is required. This paper outlines the idea of developing a mathematical model of a water-t...

High levels of measurement noise, nonlinear and non minimum phase, and conflicting performance requirements pose challenging problems for improving heat transfer efficiency and flow control in HVAC systems. This paper extends the theoretical development of the Energy Delivery Efficiency (EDE) concept to include supply air latent effects and economizer operation, defines how ideal HVAC systems s...

In order to solve the problems of a heat pump air conditioner for an electric bus under extreme conditions, such as large compression ratio, high discharge temperature, reduced system performance, frequent shutdown compressor due overheat protection, this paper proposes vapor injection technology with economizer, and carries out theoretical analysis process reveal effect on performance conditio...

This paper compares and evaluates the capabilities of six emerging diagnostic tools for commercial HVAC systems. We present a brief description of the diagnostic tools, and then focus on evaluating the features of the tools. We include the following six tools in our analysis: Architectural Energy Corporation’s ENFORMA software, Facility Dynamics Engineering’s Performance And Continuous Re-commi...

The design of two series of twin screw compressors for being used in refrigeration applications are reported in this paper. The capacity range for the open type series is from 85 to 4300 h m / 3 , and for the semi-hermetic series from 120 to 2600 h m / 3 . The rotor profile and other design parameters are optimized with the help of the software package SCCAD. Many new features are adopted in th...

Low-grade heat can be successfully recovered from waste energy sources for power production by an organic Rankine cycle (ORC). In this work, reheat ORC has been studied with three different wet fluids. The performance of R1270, R152a and Cyclopropane modelled in operated a source 413.15K. model contains economizer, evaporator, superheater, reheater, two turbine, pump condensers. With variable t...