Introduction
In the Northern Ireland, oil heating serves as the main source of heating for the domestic properties. Several investigations conducted on heating sources within the Northern Ireland have revealed that close to 65% of households depend on oil heating; however, the use of the same has been on the rise in the rural areas and the percentage stands at 80% (Lienhard & Lienhard, 2011). The original heating equipment for oil in rural areas have helped in reducing the use of energy, as well as, cost amounting to 40% besides lowering air emissions. The majority of the oil heating projects often uses proven and known oil heating options, for example, retrofits, as well as, high efficiency oil furnaces and boilers. This experiment aims to investigate the operation of a central heating system for domestic oil-fired heaters, as well as, applying thermodynamics principles for the systems analysis.
Part A: Background
One of the types of domestic oil heating system is the high efficiency oil furnaces. This type of system blows heated air via ducts delivering warm air in the entire house through grills and air registers. It is also known as a ducted warm-air distributor, and is often powered by natural gas, fuel oil, or electricity.
How it works
The gas or oil in the furnace is mixed with fuel and burned. The flames in turn heat a metallic heat exchanger, and it is at this point, where the transfer of heat to air takes place. The heated air is then pushed via the heat exchanger with the help of air handlers, fans within the furnace, and forced downwards the ductwork of the heat exchanger. The products of combustion are released via a flue pipe.
Diagram of one type of a typical domestic oil-fired heating system
One of the type of the domestic oil-fired heating system is high efficient oil furnaces, and its diagram is as shown below;
(Source: Smarter House, 2015)
(Source: Smarter House, 2015)
(Source: Smarter House, 2015)
Differences between condensing and non-condensing boilers
Alternative heating methods
Some of the alternative heating methods include solar heating systems, alternative stoves, and geothermal residential heating systems.
Solar heating systems
They usually have large, thermal mass surfaces, and south-facing windows. They often incorporate thermal mass into walls, as well as, flooring. They are composed of solar collectors, exchangers, storage tanks, heat pumps, and controls.
Geothermal residential heating systems
They use the earth’s heat as the main source of energy for heating homes. The temperature below the earth’s surface is often constant; hence, these systems can be fitted with absorbing fluids to absorb heat. The fluid is then pumped into homes to provide warmth after their heat has been extracted using heat exchangers.
Alternative stoves
They use wood, corn, as well as, pellets of wood as the main source of fuel. The fuel is burned to produce heat used in heating rooms.
Advantages
They are convenient
Fuel storage is relatively easy
The first two are clean since they do not have pollution
Disadvantages
The first two are costly in terms of installation
Alternative stoves pollute the environment
Part B: Burner Investigation
(i)
(Source: Lienhard & Lienhard, 2011)
(Source: Lienhard & Lienhard, 2011)
Main parts and their functions
(ii) (a) The mass flow rate of kerosene passing through the nozzle given the density as 810kg/m3
1 U.S gallon is equivalent to 264.17 m3, and 1 hour = 3600 seconds
V = 0.55/264.17/3600 = 5.7833 × 10-7m3s-1
The mass flow rate will be equal to 5.7833 × 10-7 × 810 = 4.684 × 10-4kg s-1
(b) Combustion equation of Kerosene
2C8H18 + 25O2 = 18H2O + 16CO2
Enthalpy change for Kerosene will be;
H̅ per mole of kerosene = enthalpy formation of reaction – enthalpy formation of reactants
= enthalpy formation of 8 moles of CO2 + enthalpy formation of 9 moles of H2O – enthalpy formation of one mole of kerosene
= (8) (-393520) + (9) (-285830) – (1) (-249950)
= - 5,470,680 kJ mol-1
H= H̅ / 114kg mol-1 = 5,470,680 / 114 = 47891.7134 kJ kg-1
Heat flow rate will be
Q̇ = H × Ṁ = 47891 / (4.684 × 10-4) = 102233245 W
C) Boiler investigation
Where M – mass flow rate, C – specific heat capacity and ∆T – change in temperature
7.5lmin×min60sec×10-3m3l×1000kgm3=0.125kgsec,where1000kgm3isthedensityofthewater
Q = u*A∆T (Torgal, 2013)
Where; A – surface area, T temperature
Inlet temperature of water is T1 -300C,
Q = uA (T2 – T1)
890330 = (0.18+2.5+0.25+0.45) * 104.72 * (T2 –303)
T2 = 890330/ (3.38 * 104.72) +303
= 28190F
The required boiler efficiency = output/ input * 100
= 85.44%
Burner efficiency = output/ input * 100
= 8.08/85* 100
= 15.28 %
The rate of heat entering the house from the boiler q1 = 224.97OD-0.7334
Where OD- occupancy density
q1 = 224.97* 2-0.7334
= 33 kWh
The concept of heat loss depends on the cooling that extracts the latent energy from the system. The procedure adopted involves deduction of energy from the energy balance. The influence of pump and fun is critical to energy dissemination in the building. The extent of heat depletion from the room depends on the base temperature of the room (Beith, 2011). The difference between the outdoor temperatures affects the level of indoor cooling rates. Heat loss will take place from all the components constituting internal elements. Therefore, detailed evaluation involves analysis of the u-values.
Heat dissipation from the house = q- u (T1 –T2)
= 33 – 3.38 (20- 0)
=33 – 67.6
= -34.84kWh
Total heat loss in 24hrs = uA∆T* 24
= -34.84*24
= -836.16kWh
D) Overall Energy Requirements
When the boiler with the rating of 33kWh supply energy into the building throughout the year in the schedule as;
Jan, Feb and Dec 6hr/day = 91* 6 = 546hrs
Mar, Apr, Oct, Nov =122*4 =488hrs
Jun, Sep = 60* 2 = 120hrs
Jul, Aug = 62* 1 = 62hrs
The annual hours of heating the home as the burner runs = 1216hours
Total energy requirement = uA∆T *hr
= 33* 1210
= 39930kWh
Conclusion
For the purposes of improving the performance, lagging is critical in retaining the heat in the system after withdrawal of heating source. The simulation of boiler and adoption of computer programs in data analysis improved data accuracy and eliminated the possibility of systemic error in the research analysis. The investigation developed the understanding of students in the field of fluid flow and boiler management.
Bibliography
Beith, R. 2011. Small and Micro Combined Heat and Power (CHP) Systems. Oxford: Woodhead Publishing.
Jenssen, T. 2013. Glances at Renewable and Sustainable Energy. London: Springer.
Lienhard, J. and Lienhard, J. 2011. A Heat Transfer Textbook. Mineola, N.Y.: Dover Publications.
Torgal, F. 2013. Nearly Zero Energy Building Refurbishment. London: Springer.
Smarter House, 2015. Types of Heating Systems. Retrieved from
http://smarterhouse.org/heating-systems/types-heating-systems. Accessed [17th March, 2016]
