A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 1994

This study was performed in order to determine the electricity conservation potential in a chosen spinning mill in Vietnam - the Hanoi Combined Spinning and Knitting Enterprise (HANOSIMEX). Attention was focused on the operation of air-conditioning system inside the mill. It was found that a significant saving of electricity can be obtained by using the open air loop operation of air washer within Hanoi weather conditions. The existing operation of airconditioning system at HANOSIMEX seems inefficient and sometimes causes negative saving in electricity consumption, due to the improperly chosen controlling method. A new operation procedure was proposed, which helps to reduce the energy consumption by almost 50%. A computer program was written in FoxPRO to facilitate the calculations. It was used to define the energy consumption and energy saving of different modes of air-conditioning system operation. The results are given in the form of daily, monthly, and annual calculations. The results indicate that OPEN-loop operation can be benefit only if the control indicator is enthalpy of air, but not temperature. Energy savings in the range of 10 to 50% are theoretically possible for air-conditioning system at HANOSIMEX. The evaluation of both technical and economic potential saving of cogeneration application was performed for existing and proposed operation modes of air conditioning system with different scenarios. The results of analysis reveal that cogeneration with double effect absorption chillers can be attractive with the existing subsidized electricity costs, if the scenario of power matching was used. Cogeneration potential can be greatly increased if the electricity cost is at the level of 550 d/kWh (about 5 cent/kWh). In combination with the proposed operation mode of air conditioning system, cogeneration will give extra saving in energy and money, compared with the proposed operation alone.