استفاده‌ي موثر از شناور حرارتي وسايل گرمايشي احتراقي به‌منظور كنترل كيفيت هواي داخل

USING THERMAL BUOYANCY OF COMBUSTION HEATERS IN ORDER TO CONTROL INDOOR AIR QUALITY

در اين تحقيق، هدف ارايه‌ي پيشنهادهاي كاربردي مناسب با ارزيابي تاثير جانمايي وسيله‌ي احتراقي و دريچه‌ي خروجي بر كيفيت هوا در فضاهاي داراي وسايل گرمايشي احتراقي، با دودكش و بدون آن است. بدين‌منظور، از بويانسي حرارتي ايجاد‌شده توسط وسيله‌ي احتراقي به‌عنوان روشي موثر در كنترل غلظت آلاينده‌ها استفاده مي‌شود. براي حل مسيله از شبيه‌سازي و حل عددي استفاده شده است. طبق نتايج حاصله، نصب بخاري در كنار ديوار خارجي، روبه‌روي دريچه‌ي خروجي و در گوشه‌هاي اتاق و نصب دريچه‌ي خروجي در مركز ديوار خارجي، به‌عنوان انتخاب بهينه پيشنهاد مي‌شوند. مقايسه‌ي بهترين و بدترين وضعيت اتاق از نظر تاثير هم‌زمان جانمايي بخاري و دريچه‌ي خروجي در كيفيت هوا نشان مي‌دهد كه غلظت CO2 در ناحيه‌ي تنفس اتاق در مدل بهينه، 9% كم‌تر از بدترين وضعيت است.

Combustion heaters can release a large amount of harmful gases, such as CO and NOx into the atmosphere of a room. But, by proper design and arrangment of the combustion equipment in the room, thermal buoyancy can be used to drive out the pollutants and improve indoor air quality. The main aim of this study is to propose a proper architectural design, and provide some practical design recommendations, by evaluating the effect of different parameters on the indoor air quality of buildings with combustion heating equipment. To achieve these goals, various arrangements for locations of heaters and outlet vents have been considered, and indoor air quality has been evaluated under these conditions by analyzing air flow and pollutant distribution due to vented and unvented heaters in the room. In order to solve the problem, a numerical simulation of the flow and pollutant fields in a 3D room was performed using Airpak software. Investigations illustrate that thermal buoyancy has different effects in various arrangements of heater and outlet vent. Changing the location of the outlet vent on the side walls cannot significantly affect indoor air quality, because natural convection currents by the heater are the dominant mechanism in flow field distribution. However, the results show that the center of a cold external wall is the best location for installing the outlet vent, so that both categories of air quality and energy combustion are considered. Moreover, the results of the present study demonstrate that the location of the heater in a room can significantly affect the distribution and also mean concentration value of the pollutants. By installing the heater near the external wall, opposite the outlet vent and in the corners of the room, 6% reduction in CO2 concentration in the breathing zone in the base model is observed. The position of the heater to the cold external wall, outlet vent, door and window are important factors that can affect the concentration of the pollutants. Generally, the lowest concentration of pollutants in the room is achieved in cases where the heater was located near the longitudinal external wall and near the corner of the room, and the outlet vent was located in another corner of that wall. Furthermore, the highest concentration of pollutants in the room was achieved in cases where the heater was located near the corner of the longitudinal internal wall, and the outlet vent was located in the corner of the transverse internal wall. Comparing indoor air quality in the mentioned conditions showed that under the best conditions, the concentration of CO2 in the breathing zone is about 9% lower than the worst conditions.