UWE Bristol Engineering showcase 2015

Ali Bin Tahir
BEng Mechanical Engineering
Project Supervisor
Dr. Aruna Palipana
Introduction:
Mechanical ventilation heat recovery system (MVHR) is a ventilation
system for the whole house with a determination of supplying and
extracting air from a house or a building. It provides a controlled way of
ventilating a home while reducing energy loss by using already
conditioned exhaust air which is to be taken out to warm or cool fresh
incoming air. This system is alternatively known as Heat Recovery Unit.
It gives a balanced low energy ventilation solution for homes and
consumes up to 95% of the heat that would otherwise have been
misspent. The system (MVHR) comprises of a network of ventilation pipes
which are connected to all the rooms in a house and a Heat Recovery Unit.
It works by continuously extracting air from rooms of the property and at
the same time sucking in fresh supply of air from outside. With the help of
heat exchanger inside the Heat Recovery Unit, the heat from the taken out
old air is recycled to heat the sifted clean supply of air for the habitable
rooms such as living rooms and bedrooms.
The Figure 1 shows a normal house fitted with MVHR system.
Figure 1
Modeling:
Figure 2 is the AUTO CAD design
of the air tight room which was
later run on CFD software to
check the air flow in the room by
placing ducts at different
positions with MVHR system
attached.
Project Title: CFD analysis of air flow inside air-tight house fitted with
Mechanical Ventilation Heat Recovery (MVHR) system.
Figure 2
CFD Study:
The images under CFD study shows the
results that were gathered by running
the model designed in AUTO CAD in CFD
software. The figures simulated comfort
temperature with four different heat
emitters, along a vertical plane at Y =
L/2. Surface temperatures of the heat
emitters’. Note comfort temperature
was similar to the middle of the room in
all cases. It was apparent that the ability
to counteract cold downdraught should
be considered in buildings where cold
fresh ventilation air is brought in directly
from outdoors. In addition, the way
ventilation inlets spread cold air into the
room should also be considered and
adapted to the heating system to
prevent cold downdraught. Traditional
radiators were found to counteract this
effect better than floor and wall heating
systems.
Project summary
This research is about the study of air flow in an air
tight room and a typical house. By the help of
AUTOCAD and CFD software we will be able to
carry out this investigation. This will be done by
modelling firstly a room fitted with mechanical
ventilation heat recovery (MVHR) system then a
model of house will be made fitted with (MVHR).
Calculations will be done to see what kind and with
what power the motor should be installed with
MVHR so that it can suck the outside air and heat it
up which will then go inside the house. The model
of a room and house will be then imported to CFD
software where the airflow will be observed and air
pockets will be observed
Project Objectives
• CFD study of the air-tight room fitted with
MVHR system
• Finding the best suitable positions for
ventilation system to be stored in a house.
• Study of air flow inside a air-tight room and a
house.
• Maintaining a good level of air quality within the
house.
• Costing of the MVHR system and operating cost
is finalized.
Project Conclusion
Firstly, a brief analysis of AUTOCAD and CFD
software has been covered. The major aims and
sub aims are examined. The specifications and
requirements have been settled for the model of
room and house. Then specifications and
requirements of air flow in air tight room and
house are established using CFD software. Detail
study of CFD study is discussed with different
scenarios that can take place while observing the
air flow and what results can be found in CFD study
is discussed with its advantages. Also a detailed
study of problems that will be faced is discussed
with its solutions.