TE LAB-PENSKY MARTEN CLOSED CUP APPARATUS

Ex.No:                                                                                                                                     Date:

 

DETERMINATION OF FLASH AND FIRE POINT OF OIL BY PENSKY MARTEN

CLOSED CUP APPARATUS

Aim:

To determine flash and fire point of a given sample of oil by using Pensky Marten closed cup apparatus.

 

Apparatus Required:

• Pensky Marten closed cup apparatus

• Oil sample

• Thermometer

 

Principle:

Flash point is the lowest temperature at which the lubricating oil gives off enough vapors that ignite for a moment when tiny flame is brought near it.

Fire point is the lowest temperature at which the vapors of the oil burn continuously for at least five seconds when a tiny flame is brought near it

 

Significance: 

Flash and fire points are used to indicate

• Fire hazard of petroleum products and evaporation loses under high temperature loses,

• It gives us the idea about the maximum temperature below which the oil can be used,

• It is used as the means of identification of specific lubricating oil,

• For detection of contamination in the given lubricating oil.

 

Procedure:

1. Check up the heater working condition of Pensky Marten closed-cup apparatus.

2. Fill up the given sample of oil up to the required level.

3. Place the thermometer and stirrer inside the oil.

4. Switch on the heater and stirrer.

5. Initially regulate the heater to rise in temperature of oil 6 o ±1 o per minute

6. On approaching the flash point the rate is reduced to 3 o ± 0.5 o per minute

7. Place the flame just above the surface of the oil.

8. At one point, a bluish flame appears and it will last for only a fraction of a second.

9. This is the FLASH point temperature of the given sample of oil.

10. Increase the temperature of the oil further and again place the flame just above the surface of the oil.

11. At one point, a reddish or yellowish flame will appear and it will burn continuously.

12. This is the FIRE point temperature of the oil.

13. Remove the stirrer from the Pensky Marten apparatus.

 

Tabulation:

Name of oil	Flash point °c	Fire point °c

 

Result:

Thus the flash point and fire point of given sample oil are found out as follows;

a) The flash point        = __________°C

b) The fire point          = __________ °C

 

PO Attainment:

Composed By:  

 R.Satheesh, M.E., Asso.Prof.,

TE LAB-CLEVELAND OPEN CUP APPARATUS

 

Ex.No:                                                                                                                                     Date:

DETERMINATION OF FLASH AND FIRE POINT

OF OIL BY

CLEVELAND OPEN CUP APPARATUS

Aim:

To find the flash and fire point of the given oil using Cleveland's apparatus

 

Apparatus Required

1 Cleveland's cup apparatus 2. Thermometer

 

Principle:

Mineral Oil when heated sufficiently to high temperature decomposes chemically to hydrocarbons & chemically breakup into volatile combustible gases. Flash point is the lowest temperature at which it forms vapours and produces combustible mixture with air. This is the formation of compressible and slightly explosive gas mixture before the surface of the oil. Fire point or the burning point is the lowest temperature at which the production of combustible gases from the oil is enough to maintain steady state after ignition.

 

Procedure:

• The open cup is filled with the given sample oil up to the standard filling mark in the cup.

• The thermometer is held in the oil in such a way that it does not touch the metallic part.

• The sample of oil is heated so that it gives on vapor.

• At the testing time the test flames is applied by heating short distance over the surface of oil and watched for flickering sound.

• The minimum temperature at which a momentary flash is obtained is called flash point.

• Heating is continued after obtaining the flash point. The lowest temperature at which the ignited vapour continues to burn is called fire point.

• Note the flash point and fire point of the given oil in a separate tabular column.

 

Tabulation:

Name of oil	Flash point °c	Fire point °c

 

Result:

Thus the flash point and fire point of given sample oil are found out as follows;

a) The flash point        = ___________°C

b) The fire point          = ___________ °C

PO Attainment:

Composed By:  

 R.Satheesh, M.E., Asso.Prof.,

TE LAB-DETERMINATION OF COP OF A REFRIGERATION SYSTEM

Ex.No:                                                                                                                                     Date:

DETERMINATION OF COP OF A 

REFRIGERATION SYSTEM

Aim:

To determine the [i] Theoretical COP, [ii] Experimental COP, [iii] Carnot COP, [iv] Relative COP on a refrigeration system.

 

Facilities Required and Procedure:

Description

Vapour compression cycle is widely used refrigeration cycle. The main object of the trainer is to demonstrate refrigeration system with basic components and necessary controls. The practical working is demonstrated in the system and considerable amount of theoretical analysis and performance can be studied.

The trainer consists of components of a refrigeration system viz. Hermetically sealed components, evaporator, condenser, capillary tube. The condenser is air cooled type for which a condenser fans and motor has been provided. Evaporator is water immersion type which is housed in a thermally insulated calorimeter. Calorimeter is provided with an electric heater which can be used for heating the water initially to be desired temperature.

In addition to capillary tube a thermostatic expansion valve is also provided. We have to select either a capillary tube or thermostatic expansion valve at a time. A toggle switch has been provided to facilitate this selection.

A temperature indicator with six point selection switch has been provided to get the various temperature of Freon-12 viz. Compressor suction, compressor discharge after condenser and after expansion and water temperature.

Special gauges have been provides for indicating Freon-12 pressure at above mentioned points except for colorimeter water.

An energy meter has been provided which indicates the consumption of energy of compressor. An additional energy meter has been provided to indicate the energy consumption of water heater.

The students are advised to find out the saturation temperature of F-12 after knowing the pressures at various points and based on the saturation temperatures study the working of refrigeration considering the cycle based on

[a] Reversed Carnot cycle,

[b]  Simple vapour compression cycle.

 

Specification:

Compressor: Hermetically sealed compressor.

Air cooled condenser.

Expansion valve:

(a) Capillary tube.        (b) Thermostatic Expansion valve.

Evaporator.

Rota meter: For liquid refrigerant flow rate.

Refrigerant: Freon-12.

Energy meters for power measurement of compressor and the fans and heater.

Pressure gauges - 4 Nos. (Two for H.P. and Two for L.P.)

Temperature indicator.

Solenoid valves.

H.P. / L.P. cut out.

Ammeter, Voltmeter, Thermostat.

c] Procedure for doing the experiment:

Specimen Calculations:

P₁ = Pressure of the Condenser inlet.               P₂ = Pressure of the Condenser outlet.

P₃ = Pressure of the Cooling inlet.                    P₄ = Pressure of the Cooling outlet.

Sensor Meter Reading:

T₁ = Temperature of Compression Outlet         T₂ = Temperature of Condenser Outlet

T₃ = Temperature of Capillary Outlet               T₄ = Temperature of Cooling Coil Outlet

T₅ = Temperature of Cooling Coil

TABULATION:

S. No.	Time	Energy Meter Reading For 10 Rev. in	Pressure				Temperature
			P1	P2	P3	P4	T1	T2	T3	T4	T5
1
2
3
4
5

 

Formula:

Ø  Total Refrigerating effect Q = mCp DT/Dt.

Where, m = Mass of water in kg.

Cp = Specific heat of water = 4.186 KJ/kg.

DT = Temperature drop in the water.

 

Ø  Theoretical COP = [h₁ - h₃]/ [h₂ – h₁]

[Enthalpy is to be found out from the P-h diagram of R-12]

Where,

      h₁ = Enthalpy corresponding to pressure P₁ and refrigerant entering temperature at T₁°C.

h₂ = Enthalpy corresponding to pressure P₂ and refrigerant leveling temperature at T₂°C.

h₄ = h₃ = Enthalpy corresponding to pressure P₃ and refrigerant temperature after condensing at T₃^o C.

 

Ø  Experimental COP = [Actual Refrigeration Effect/time] / Workdone.

Actual Refrigeration effect/time = mCp DT/Dt.

Where, mw = mass of water in kg.

Cp = Specific heat of water = 4.186 KJ/kg.

DT = Temperature drop in the water.

Workdone = Energy consumed by the compressor motor to be found out from the energy meter. Workdone = (10/t) x (3600/e) x 0.9.

Where, e = Energy meter constant = 1500 rev./kW-hr.

t = Time taken in sec. for 10 revolutions of energy meter reading.

Experimental COP = mCp DT/Dt / workdone.

 

Ø  Carnot COP = T_L / [T_H - T_L]

T_L = Lowest Temperature from table at corresponding to P_min

Where,             P_min = [P₁ + P₄] / 2    bar

T_H = Highest Temperature from table at corresponding to P_max

Where,             P_max = [P₂ + P₃] / 2   bar

 

Ø  Relative COP = Actual COP / Carnot COP

 

Result:

The COP of the Refrigeration system were determined and tabulated.

Theoretical COP	Experimental COP (Actual)	Carnot COP	Relative COP

PO Attainment:

 

Composed By:  

 R.Satheesh, M.E., Asso.Prof.,