in 4th semester mechanical engineering thermodynamics practical

1. Boy’s Gas Calorimeter
NAME : Dilshan K.M.G.L.
COURSE : BSc. Engineering
INDEX NO. : 150****
GROUP :
DATE OF PER. :
DATE OF SUB. :

2. Abstract
In this practical we are going to find the calorific value of LP gas. Basically, calorific value
represents the energy, heat we can get by burning fuel. We are trying to get some knowledge how the
calorific value is changed according to the gas parameters, like volume flow rate, pressure of the gas
etc.
These results can be used in industry as well as domestic works to increase the efficiency of the work
and generate heat through the burning process efficiently. Here if can use higher calorific value
parameters through the burning process, or set the parameters to that values, according to the theory,
we can generate higher heat.
The results we get from the practical can be include to the practical scenarios and get the benefit of it.
Ans also the values that we can calculate the calorific value in theoretical are developed using
empirical calculations. So that we can conclude, the practical values can be directly applied to the
real-life problems to enhance the duty of work.

3. Introduction
Boy’s gas calorimeter was designed to get accurate values of the higher and lower calorific value of
given fuel. Mainly we can measure the calorific value of gaseous fuels only because the practical
apparatus was designed for that purpose.
First, when consider about the calorific value, by definition, it is the total energy released when
completely combusted with oxygen at standard conditions. Standard condition means 0℃ and 1 atm
(1.023 bar). In nut shell, calorific value represents energy that transferred in to surrounding pre- unit
quantity of fuel at constant pressure. The gas calorimeter is designed to make sure that the heat from
the burner flows up through the calorimeter container and back down again inside the container and
back up again before exhausting.
In engineering point of view, we have to consider methods that can extract higher heat or energy
from the burning process and follow the process, less amount of energy released or waste. After some
calculation and empirical procedures, with the state of the water in the combustion products, energy
can get from the combustion is varied. The values that represents higher heating value and lower
heating value are respectively when water is in liquid form and in gaseous form. Basic theory is
energy absorbed by the water when evaporating to the surrounding causes to reduce the heat output
from the process. So that through this practical we can measure the difference of the HCV and LCV
of the liquid petroleum gas.
Higher calorific value has higher energy, as by the name of it than the LCV. But from the application,
we have to select appropriate conditions. Some of the process is being disturbed by the higher heating
values because of the condensed water, also on the other hand some of the process is being disturbed
because of the formation of the water vapour. Ans also these values are calculated under standard
conditions because the ease of the comparison. So that the state that we are going to choose is much
more important in practical cases.
When we consider about the practical applications of the calorific value, we come to know that there
are many apparatuses rather that Boy’s gas calorimeter. Basically, bomb calorimeter is used to
measure the calorific value of liquid and solid fuels. Basic practical application is the use of fuel oil,
gasoline or petrol, coke, coal, combustion water, foodstuffs and building materials. Also, these
calorimeters can be used to measure the energy balance of Nano- material and ceramics. When
consider all together calorific value is important to study and compare the values of combustible
materials and usages of them.
When new fuel is found or invented, engineers and scientists are checked the usages of that fuel and
also have to report the efficiency of it. So, in the evaluation process, to calculate and measure the CV
values use these calorimeters.
Also, we have to measure the amount of fuel that is going to use during the process. So that have to
calculate amount of heat and through that have to calculate the mass or volume of the fuel. That is
important when we have to take the fuel to another place. For that purpose, we can get the resultant
values of that practical.
In conclusively, we can say that CV of a fuel plays major role in the engineering field and industry to
make sure the process is on the efficient way and economical way.

4. Theory
Calorific value is defined as total energy released when completely combusted with oxygen at
standard condition. (0℃, 1 atm)
When we consider about the heating value, amount of energy released when a fuel is burnt
completely is steady flow process and the products are returned to the state of the reactants.
There are two calorific values are defined according to the state of the water at the combustion
products.
1. Higher calorific value, higher heating value – when H2O in the product is in the liquid form
2. Lower calorific value, lower heating value – when H2O in the product is in the gaseous from
HV is equal to the absolute value of the enthalpy of combustion of the fuel at a specified state.
HV = |hc|
Basic relation of HCV and LCV is
HCV = LCV + (Nhfg)H2O
With the results of the practical, can calculate the LCV.
• Gas volume = volume flow rate × time (cm3
)
• Gauge pressure = value × 10 × (
1000
13600
) (cmHg)
• Absolute pressure = Gauge pressure + Atmospheric pressure (cmHg)
• Correction of gas volume (V);
𝑃1 𝑉1
𝑇1
=
𝑃2 𝑉2
𝑇2
• Increased temperature = 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑜𝑢𝑡 − 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑖𝑛 (𝐾)
• Latent heat (Q) = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 × 𝑠𝑝𝑒𝑐𝑡𝑓𝑖𝑐 𝑙𝑎𝑡𝑒𝑛𝑡 ℎ𝑒𝑎𝑡 (𝑘𝐽)
• HCV =
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑐𝑜𝑜𝑙𝑖𝑛𝑔 𝑤𝑎𝑡𝑒𝑟×𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 ℎ𝑒𝑎𝑡 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦×𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑖𝑛𝑐𝑟𝑒𝑚𝑒𝑛𝑡
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑓𝑢𝑒𝑙 𝑢𝑠𝑒𝑑 𝑎𝑡 𝑔𝑖𝑣𝑒𝑛 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛

5. Equipment
• Boy’s gas calorimeter
• Thermometers
• Manometer
• Water circuit
• Stopwatch
• Constant pressure head
Procedure
1. The upper part of the calorimeter is removed, opened the gas flow and lit up the burner.
2. Constant pressure head is set to the apparatus and opened the water flow.
3. The stop watch was set and at that moment water direction is changed to collect the water that
circulating through the apparatus.
4. Water is collected that circulate through the calorimeter for 5 minutes.
5. Temperature readings were taken after 5 minutes collecting the water.
6. Volume flow rate was taken by the flow meter and readings were calculated with the help of
given chart.
7. All the values are noted down and calculated the HCV.

6. Calculation
For case 2
Volume flow rate = 121 (𝑐𝑚3
/min)
Gauge pressure−0.2 (𝑚𝑚𝐻2 𝑂) = −0.14706 (𝑚𝑚𝐻2 𝑂)
Absolute pressure = 75.90 (𝑐𝑚𝐻𝑔)
Inlet temperature = 32 ℃ = 305.15𝐾
Exhaust temperature = 32 ℃ = 305.15𝐾
Volume flow rate (27℃ 1.023 bar) =
75.83
76.73
×
273.15+27
305.15
× 121𝑐𝑚3
/𝑚𝑖𝑛
= 117.7325𝑐𝑚3
/𝑚𝑖𝑛
Elapsed time = 5 𝑚𝑖𝑛
Corrected volume (27℃ 1.023 bar) =588.66𝑐𝑚3
/𝑚𝑖𝑛
Cooling water parameters
Volume collected = 1895𝑐𝑚3
= 1895𝑔 = 1.895𝑘𝑔
Inlet temperature = 29℃ = 302.15𝐾
Outlet temperature = 35℃ = 308.15𝐾
Specific heat capacity = 4.178 𝑘𝐽/𝐾. 𝑘𝑔
hfg = 2564.6 kJ/kg
HCV =
1.895×4.178×(35−29)
588.66×10−6 = 110013.96 𝑘𝐽/𝑚3
Results
Practical Number 1 2 3 4 5
Volume flow rate (cm3
/min) 50 121 162 221 282
Gauge pressure (cmHg) -0.22 -0.15 -0.15 -0.15 -0.15
Absolute pressure (cmHg) 75.83 75.9 75.9 75.9 75.9
Volume flow rate (27℃ 1.023 bar) 48.76 117.73 157.1 213.62 271.7
Corrected volume (cm3
) 243.8 588.65 785.5 1068.1 1358.5
HCV (kJ/m3
) 110019.52 80699.67 65555.51 41776.09 33583.92

7. Discussion
• Usefulness of this lab exercise. Situations and places that the results are being used in industry
and engineering design
Since there are lots of power sources are available, fuels are acting prominent role. Variation
of the fuel is much larger and usage of the fuel spread through various parts. There must be
some characteristics that use to classify fuels. HCV and LCV values of the fuel is significant
in that process.
When we consider about the difference of the HCV and LCV values, we cannot say that HCV
value is always use in application. But with the use of the application, choice will change. As
an instance if the condensing water is making trouble and when we have some chance to
produce water steam, we have to use LCV value than HCV value without considering the heat
loss. On the other hand, if the steam is preferring to use rather than the liquid water, we can
use LCV states, that is the efficient way.
On the other hand, that values, HCV and LCV, are representing the energy that can extract
from the fuel for unit volume. In solid fuel we can use energy extract from the unit mass. On
the other hand, we can use these values to compare different fuels and can select most suitable
fuel to the situation.
In engineering application, these values can be to enhance the design and efficiency. And also
with the change of fuel and fuel type, the volume and capacity of the machine can be reduced
and the extra cost can be removed and expensiveness can be reduced. And also, durability of
the machine can be enhanced using that values.
Most of the power plants that use fuels to produce steam, are use these values to compare the
efficiency and the reduce of the expensiveness of the unit energy that produced by the power
generation unit. And also in engine and other machines, these data values can be used to
compare the most prominent fuel.
Some of the engineering applications that use these data values are in vehicles, ships, power
plants, aircrafts etc.
• Use of calculate the latent heat of steam at 25℃ in calculating the lower calorific value
Here we can use latent heat of steam at this temperature to calculate, but these values will
make some error because latent heat of energy is changed with the temperature. So that in
higher temperatures that we were used to do the practical, the value of latent heat is changed
and for the improvement of the accuracy have to use correct values. And also, the temperature
is changed with the time during the practical. That is another error.
• Relative merits of the use of HCV and LCV in power plant thermal efficiency definition.
In most of the cases, when calculating the power plant efficiency, here use combustion
efficiency and that directly affected to the overall efficiency. In combustion efficiency is
directly involved with the HCV and LCV. So that we have to consider some methods that can
extract heat and energy from the fuel to the power plant by reducing the energy wastage.
When we consider about the power plant due to the higher temperature, there is no chance to
water at the liquid state, so that there must be use the LCV values to the calculations. But in
the definition of the efficiency of the power plant, it considers maximum energy that have to
deliver to the power plant, so that have to use HCV values. So that the difference of the actual
and theoretical are occurred.

8. • Difference of the high and low calorific values in different gas flow rate.
Most of the time, when the source of energy is transferred in higher mass flow rate or higher
volume rate, the energy produced by the fuel is increasing, because fuel partials and oxygens
are reacting higher speed and also the percentage of the complete combustion is increased. So
that calorific values are changed with the increment of the fuel flow rate,
And other thing is we are doing these calculations under some assumptions, because we
cannot keep the conditions constantly throughout the process. Basically, we assumed that fuel
gas is ideal, not real. But actually, cases this not true. And also heat loss by the calorimeter is
assumed as zero. Another thing is fuel is burnt completely.
In the temperature readings and volume flow rate readings are changed due to the small part
of divides of the thermometer. The least count of the measuring equipment is low. So, the
reading error will have caused because of the measurement.
To reduce the heat dissipation from the calorimeter, have to use polished surface on the
calorimeter. And also, can use insulating materials.
• Use of measuring HCV and LCV by using this experiment setup.
Basically, this experiment setup can be used to analyses the other gaseous fuels, but cannot be
used to measure the HCV or LCV values in solid fuels. Main reason is most of the solid fuels
cannot be combusted completely under these conditions. Some of the combusts and some
other parts of the combustion are remains after burning. And also, liquid fuels like patrols and
kerosene will produce vapour of the fuel. So that some of the burning fuels will remove with
the exhausting products.
There is a method called bomb type calorimeter that can be used to measure the calorific
value of solid and liquid fuels.
Conclusion
• Two calorific values can be measured using this process by considering some assumptions
and have to use error reducing methods.
• Efficiency of the fuel can be evaluated using these HCV and LCV values.
• Can select suitable fuel that has suitable capabilities for the corresponding application.
• Boy’s gas calorimeter can be used to can calculate HCV and LCV values.
References
Michael J. Moran, H. N. (2006). Fundamentals of Engineering thermodynamics. West Sussex:
John Wiley & Sons, Inc.