ACCOUNTING FOR NONUNIFORMITY OF WATER CONSUMPTION IN THE EXHAUST AIR HEAT RECLAMATION SYSTEMS FOR HOT WATER SUPPLY

• Main Author: Samarin Oleg Dmitrievich
• Format: Article
• Language: English
• Published: Moscow State University of Civil Engineering (MGSU) 2017-03-01
• Series: Vestnik MGSU
• Subjects: energy saving; heat reclamation; heat exchanger; temperature efficiency; Monte Carlo method
• Online Access: http://vestnikmgsu.ru/index.php/archive/article/download/3623

This article is devoted to assessment of the influence of variation of daily hot water consumption on the predicted energy effect by using heat recovery of exhaust air in typical exhaust ventilation systems of the most commonly used flat buildings during their switch to the mechanical induction for the pre-heating of water for hot water supply. It outlines the general principle of the organization of this method of energy saving and presents the basic equations of heat transfer in the heat exchanger. The article proposes a simplified method of accounting for changes in the heat transfer coefficient of air-to-water heat exchanger with fluctuations of water demand using existing dependencies for this coefficient from the rate flow of heating and heated fluid through the device. It presents observations to identify the parameters of the real changes of water consumption during the day with the main quantitative characteristics of normally distributed random variables. Calculation of thermal efficiency of the heat exchange equipment using dimensionless parameters through the number of heat transfer under the optimal opposing scheme of fluid motion is completed under conditions of variable water flow rate for the type residential building of the П3-1/16 series using the Monte Carlo method for numerical modeling of stochastic processes. The estimation of the influence of fluctuation of the current water consumption on the instantaneous thermal efficiency factor of the heat exchanger and the total energy consumption of the building is given, and it is shown that the error of said calculation using average daily parameters is within the margin of usual engineering calculation.