As a result in many mines work place environment has become oppressive and affecting the productivity and safety. The importance of ventilation has been ...
EFFECT OF AUTO COMPRESSION ON VENTILATION SYSTEM OF DEEP SHAFT COAL MINES IN JHARIA COAL FIELD – A CASE STUDY D. Mishra* and Dr. N. Sahay** * Trainee Scientist, ACSIR, CSIR-CIMFR, Dhanbad **Sr. Principal Scientist & Head, Mine Ventilation Discipline, CSIR-CIMFR, Dhanbad 1.0 ABSTRACT The future prospect of underground coal mining in Indian mines is either from extensive mines or at depth (> 300 m). In this situation the intake air is expected to be influenced by various parameters, viz. auto- compression, surface air temperature (seasonal temperature variation), heat due to explosive detonation, heat from mechanized equipments, metabolic heat, heat from broken rock, wall rock heat flow, heat from other sources etc. Many mines in our country are receding towards lower horizon by taking the liability and responsibility of upper seams. In order to address the problem of oppressive climatic conditions at the workings, behavior of various parameters affecting the quality of intake are required to be studied for realistic ventilation planning of deep mines. The effect of auto compression is one of them. The paper deals with realistic estimation of heat addition to the intake air due to auto compression.
2.0 INTRODUCTION Many Indian coal mines have become extensive or receding towards greater depth. As a result in many mines work place environment has become oppressive and affecting the productivity and safety. The importance of ventilation has been realized since beginning of mining operation. It has been established that it has got direct relation with production, productivity and safety of the mines. In a study [1] the relation of wet bulb temperature at workplace environment and efficiency of the workers has been established. On the basis of literature, in US metal mines maximum efficiency is at or below 270c and economical efficiency is between 270C to 290C. In addition, the inspectorates of different coal producing countries have also stipulated the value of maximum permissible wet bulb temperature as per their climatic condition considering the miners health. These values are for coal mines India [2], USA [3], UK [4] are 33.50C, 300 c, 330C respectively. It has also been established that the temperature of the environment can be diluted by increasing the air quantity at the workings. For determination of optimum value of air quantity at particular workings depend on physical parameters of the openings and thermal properties of the virgin rock etc. For deep shaft mine heat due to auto compression plays an important role in adding enthalpy to the air flowing in the mine. Auto compression [5] is considered as a source of heat which can’t be diluted by increasing air circulation in mine. In case of shallow depth mines effect of heat due to auto compression is considered negligible. However in case of deep shaft mines auto compression of intake air in shaft raises the temperature affecting the workplace environment. This subject gets more complicated day by day as the Indian coal mines are receding towards a greater depth i.e. (>300m depth). Therefore consideration of auto compression on air current in deep shaft mines is necessary. The paper discusses the effect of auto compression on air in one of the mines in Jharia coal field of Tata Steel Ltd.
3.0 History of auto compression in Indian mines Value of [6] rise in dry-bulb temperature of air due to auto compression is 0.976 K per 100 m depth. The wet-bulb temperature of air also rises due to auto compression but its rate depends upon surface dry-bulb and wet-bulb temperature. For prevalent summer conditions in India the wet-bulb rises at the rate of 0.3-0.25 K for every 100 m depth in dry air, but as soon as the evaporation in shaft occurs then the dry-bulb temperature decreases sharply and wet-bulb temperature rises at a faster rate. In this condition the adiabatic index of the intake air can be represented by
1
a variable polytropic index (n). In dry shaft (n) approaches( 𝛾), in wet shafts (n) can be equal to 1.0 (isothermal compression) or even less than 1.0 because of evaporation of water in the downcast shaft which lowers the dry-bulb temperature.
3.1 AUTO COMPRESSION IN MINES 3.1.1 The air while descending gets compressed by the columns of air and subsequently gains heat. In dry shaft the air gains heat due to adiabatic compression resulting in addition of sigma heat to the air current. It is calculated using formula [7]. Temperature rise (0c) = =
increase in heat content of 1 kg of air specific heat of air(Cp) mass × gravitational acceleration ×distance specific heat of air(Cp)
----- (1)
3.1.2 The another approach for calculating the temperature of the air in the shaft, considering potential energy of the air in the shaft gets converted to heat energy provided no work is done by the air descending the shaft, (i.e. the flow is frictionless and non –accelerative) and no heat or moisture is lost or gained by the air, then the compression of the air in the downcast shaft will be reversible adiabatic [8]. 𝑇2 𝑇1
= (𝑃2/𝑃1)𝛾−1/𝛾 = (𝑉2/𝑉1)𝛾−1 -------- (2)
Where T = temperature, K 𝛾 = Cp/Cv = 1.404 for dry air (it varies slightly with the moisture content of air, but for mining purpose it can be taken as equal to 1.4), V= specific volume (volume of unit mass of air), P = barometric pressure, kPa, Subscripts 1and 2 indicates the state of air at shaft top and bottom respectively. By finding barometric pressure at shaft top the temperature rise due to auto compression can easily be calculated. The temperature rise due to auto compression can also be calculated by equating the potential energy with the enthalpy change in the downcast shaft. This follows the relation given below: dQ – dW = dH + dPE + dKE ------- (3) Where dQ = heat added to or removed from the section (from outside the system), dW = external work done on or by the fluid in the section, dH = change in enthalpy of the fluid across the section = gdh, dKE = change in kinetic energy of the fluid across the section = d (v2/2) = vdv, dPE = change in potential energy of the fluid across the section, g = acceleration due to gravity, h = elevation of the fluid, v = velocity of the fluid. Under the assumptions made dQ = 0, as no heat is transferred, dW =0, as no work is done on or by the fluid, dKE = 0, as the flow is nonaccelerative. So that the equation becomes = dH = - dPE. Now from the above relation it can be concluded that the heat source due to auto compression is = ∆H = mgh = m.Cp.∆T = ∆ T = ∆H/ m.Cp ----- (4) Where ∆T = rise in temperature, K, ∆H = change in enthalpy, J/kg, h = depth of the shaft, m, Cp = specific heat of air, J/kg.K, m = mass of the air column descending in the shaft, kg 3.1.3 Further it is explained [9] that apart from geothermal effect; air in underground mines is also heated due to effect auto compression. As the air goes down a shaft or incline gets compressed by the column of air above, its enthalpy is increased due to conversion of potential energy (I) to heat energy. For enthalpy change energy balance equation is H2 – H1 between top and bottom of a shaft at Z1 and Z2 (m) above datum per Kg of dry air is given by; H2 – H1 = g (Z1 – Z2) -------- (5) The theoretical rise of temperature is∆𝑇 = 𝑇2 − 𝑇1 =
𝐻2−𝐻1 𝐶𝑝
=𝑔
(𝑍1−𝑍2) 𝐶𝑝
------------ (6)
0
Where CP is in j/kg. C.
2
3.1.4 The auto- compression can also be treated as adiabatic compression in the shaft [10]. When there is no heat exchange in the shaft and no evaporation of moisture takes place. Heat due to auto- compression in vertical shaft is calculated by the formula q QpE T --------------------- (7) Where q = theoretical heat of auto compression (W), Q = airflow in shaft (m3/s), 𝜌 = air density (kg/m3) and ∆d = elevation change (m) 3.1.5 Air auto compression in inclined raise layout Auto compression process occurs during the air descend through the underground openings and due to its own compression. The mathematical model [11] is deduced considering the equilibrium condition, air properties and the influence by the vertical forces as situation presented in Figure (1) In this case depth h can be expressed as a function of underground opening length L (m) and inclination α ( 0), and can be written as h = Lsinα and finally the temperature increased in underground opening due to auto – compression is ∆ta (0).diagram.
.
α
Figure-1
Figure- 1- air auto compression in inclined raise layout g.dh – dp/ρa = 0 ---------- (8) Where, g is gravity, dh is depth differential, and dp is pressure differential, ρ is air density. dh=dp/γ=vdp ------------ (9) Where γ is specific gravity, v is specific volume v.dp + k.p.dp = 0 ------------- (10) Where in adiabatic process p.vk =constant, k is air adiabatic coefficient. According to Clapeyron equation p.v = R.t2, R is universal gas constant and t2 is the compressed air temperature. p.dv = R.dt2 – v.dp ------------ (11) using equations (10), (11) and(12) the following equation is obtained dh + k(Rdt2 - dh) = 0 ------------ (12) (1-k)
dh k.R dt 2 = (1-k)h + k.R.t
2
+ C = 0 ------------ (13)
Where C is constant. Rearranging equation (14) we get the temperature t2 as t2 = (k-1)h/ k.R – C ∆ta = t2 –t1 = (k-1) h/k.R
---------- (14) ----------- (15)
3
Now putting the values of (R = 29.7 kgf-m/kg.0k) and average air adiabatic index (1.302) the final equation is obtained as follows:
t2 –t1 = 0.0098h
∆t a = t2 –t1 = 0.0098Lsinα
------------ (16) ------------ (17)
3.1.6 In case of moist air, the specific heat per Kg of dry air is slightly more and dependent on moisture content of air, provided there is no increase in moisture content from water evaporation. Rate of increase of WBT with depth is independent of the initial WBT of air. For Indian coal fields the rate of rise of wbt is 0.25-0.3 0C/100 m depth. Hence due to the above reason the rise of DBT due to auto compression effect becomes less and on the other hand the WBT rises more than the above rate. There is another derivation [12] for calculation of heat source added in the mine environment due to auto compression of air in the shaft the following procedure is followed; T2/T1 = (P2/P1) (γ-1/γ) ----------------------- (18) 0 Where T = absolute temperature ( K), P = atmospheric pressure (kPa), γ= ratio of specific heats of air at constant volume and pressure, and subscripts 1 and 2 refers to the initial and final conditions respectively. Values of γ are 1.402 for dry air and 1.362 for saturated air. Hence in actual mining condition there may be both dry and wet conditions. The contribution of auto compression in rise of temperature in mine airways as calculated by the formula [13] is about 40-60% of the total.
4.0 INVESTIGATION About the experimental site NO.2 Pit Jamadoba Colliery belongs to Jharia group of mines of Figure-2: showing the seam wise entry and exit of the mines Tata Steel Ltd is located on the west side of Jharia- Sindri Road No.2 ,3&4 PITs JAMADOBA COLLIERY, TISCO and about 5 Kms from Jharia Township. The position of the [UC] [DC] NO. 2PIT NO. 3 PIT NO. 4 PIT colliery as per geological map is latitude 23 41’40” to 23 43’00” N and longitude 87 24’30E. The Mine is surrounded on the North: Jitpur colliery Keduadih colliery and Bhutgoria colliery on the South: Bhowrah colliery, on the East Digwadih colliery:and on the XVIII XVIII XVIII West Amlabad colliery. It is captive mine having very bright future prospect as mine able coal reserve about 25 million tonnes. The XVII XVII XVII estimate life of the mine may be more than 50 years with existing production rate [@500 tons/day]. In the mine there are three Pits, XVIA XVIA R R viz. No.2, No 3 and No 4 . Among them Pits No. 2 and 4 are XVI XVI acting as downcast while Pit No. 3 Pit acting as upcast. Intake air from Pit No-2 is utilized for the ventilation of main workings of XI XVA seam. Hence, Pit No-2 (Depth: 374.8m, Cross sectional area 21.7 m2] is considered for the study. Layout of the shaft with seam Figure-2 entries is shown in Figure 2. Air enters through Pit No.2 travels XV along 3 -X-cut up to 10L- air crossing at 14L- drift mouth - XI XIV seam intake to 1st rise (1L) –working at22L in XI seam. The ventilation system in the mine is exhaust with homotropal transportation system. The ventilation is achieved by axial flow fan (Make: Voltas, Model: VF-300) handling air quantity about 116 m3/s at pressure of 106 mmwg. Air quantity flowing through Pit no. 2 was of the order of 74.08 m3/s. A schematic diagram of ventilation network of the mine is shown in Figure 3.
4
2 P IT
Ventilation network jamadoba colliery(not to scale)
4 P IT 3 P IT
FAN HOUSE
4A
4B
A-
0
18 S eam
4
2
R 18 S eam
R 200
0 16 16 S eam/2 P it Dam R
1401 160 H
C -2
16A S eam
R
B Dip
S taple S haft
9th L /B -dip
10th L
31s t L P ump 1s t X C ut 27 L
2nd X C ut
6th L 3rd C ros s C ut
i ft -I
125 H
R
R
12th L
14 S eam/2 P it
16 S eam/Dip
15th L
1s t Dip
S ump drift
2 P it drainag e drift
B -1
i ft - II
C -5 B elt
17 S eam
A -1
B -2
16 L
26 L
R
4th X C
Dr
5th X C
-1s t dip
18 0 R is e 3 rd R is e 4th R is e 5th R is e
L th
Ventilation Network J amdoba C olliery ( Not to s c ale)
R
28 L
Dr
1120 Dig wadih
17 S eam
6L 3 P ump
S towing drift
25
E twari S ing h drift
14 S eam/P attia
Figure -3: A schematic diagram of the ventilation network of Jamadoba colliery
Experimental design Ventilation circuit extended from surface - Pit No.2 bottom – XI seam via XIV seam was divided into seven segments. Details of the segments are furnished in the Table-1.. TABLE- 1: Details of the segments SegmentLocation Length(m) Area(m2) Perimeter Depth of Depth of no (m) out let (m) inlet (m) 1
Surface to pit bottom
375
21.07
16.27
0
374.8
Angle of Inclination ( O) 90
2 3 4 5 6 7
Pit bottom to 3-X(10L) 3-X(10L) to air crossing at 14L air crossing at 14L to drift mouth Drift mouth to intake to XI seam XI seam intake to 1st rise ( 1L) 1st rise ( 1L) to XI seam workings
650 180 50 275 50 450
9.81 9.93 9.46 10.75 12.24 11.81
13.55 12.94 13.39 13.76 14.36 15.00
374.8 442.3 458.2 460 523.9 525.3
442.3 458.2 460 523.9 525.3 542.2
6 14 5 2 13.5 2
5
Experimentation The results of investigation comprising measurement of air quantity, wet and dry bulb temperatures are furnished in Table -2. Table2-Results of measurement of air quantity, wet and dry bulb temperatures segment wise Sl no Segment no Air quantity(m3/s) WBT DBT Wetness in (0C) (0C) (%) 1
Segment-1
74.08
32.50
27.50
70
2 3 4
Segment -2 Segment- 3 Segment- 4
30.89 30.33 30.03
31.70 31.60 31.60
28.90 31.40 31.40
30 20 20
5 6 7
Segment -5 Segment- 6 Segment- 7
30.01 29.98 18.21
32.20 32.70 33.40
31.90 31.80 32.60
30 60 70
TEMPERATURE(0C)
VARIATION OF TEMPERATURE IN U/G WITH DISTANCE 34 33 32 31 30 29 28 27 26 25
DBT(0C)
WBT(0C)
375
1025
1205
1255
1530
1580
2030
DISTANCE,(m)
For determination of effect of auto compression the segment -1 ( Pit No.2) was divided into four sub segments. , viz, surface - 100m depth, 100m - 200m depth, 200m -300m depth and 300m – 374.8 m depth. Results of measurements of air quantity flowing in Pit No.2 and wet bulb & Dry bulb temperatures at the end of sub segments are furnished in table -3 Location
Air Quantity (m3/s)
DBT (0C)
WBT (0C)
1
Pit- top(0 m)
74.08
28.5
25.5
2
100 m
28.0
26.0
3
200 m
28.0
26.5
4
300 m
27.5
27.0
5
Pit-bottom(374.8 m)
29.0
28.5
Sl-no
6
Psychometric properties, viz. density, specific enthalpy, total enthalpy, total sigma heat and dew point of air quantity flowing through the above segments were calculated by using software based on the formula[14] given below: The results are furnished in Table -3 (i) True density of air-water vapour mixture(wt, kg of air –water vapour mixture/m3): wt = 1/vt ------------------------ (19) (ii)
Enthalpy of air-water vapour mixture(H,Kj/kg of air): H = 1.005tdb + r(2.5016 + 0.0018tdb) ---------------- (20)
(iii)
Where tdb = dry-bulb temperature (0C); r = moisture content (g of vapour/kg of air) Sigma heat(S, Kj/kg of air) S = H – 0.004187rtwb ---------------- (21) Where H = enthalpy of air-water vapour mixture (H, Kj/kg of air); r = moisture content(g of vapour/kg of air); twb = wet-bulb temperature(0C). During any adiabatic saturation process, the sigma heat remains constant (but not the enthalpy) and the use of sigma heat in calculations involving wet heat transfer is more accurate than when the enthalpy is used.
(iv)
Dew point temperature(tdew,0C): tdew = 237.3 loge (e/610.5) ÷ 17.27 – loge(e/610.5) ---------------- (22) Where e = vapour pressure (Pa)
Table-4: Psychometric properties of air flowing through different segments S.No
Segments
Sub segment
1.
2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
Mass flow (kg/s)
Sp. Enthalpy (kJ/kg)
Surface
1
2 3 4 5 6 7
I II III IV I 1 I I 1 I
Relative humidity (%) 78.74
87.717 87.674 87.765 87.225 37.917 37.279 37.294 36.960 36.907 22.111
79.54 81.65 83.92 90.89 93.19 93.58 94.13 94.23 95.46 108.56
85.42 88.96 96.21 96.22 97.03 96.31 96.31 96.34 96.34 94.54
7
4.2 Calculation of temperature due to auto compression The value of actual temperature rise due to auto compression in the air descending through Pit No. 2 was calculated using formulae given by different researchers at different depths. The results are furnished in the table-5. Table -5- Temperature (t) of air descending through Pit No.2 at different depth due to auto compression ( OC).
Equation No.
formula used
100 m
200 m
300 m
374.8 m
1 2
(t)=m.g.h/cp (t)=g.(h2 - h1)/cp
0.98494 0.976119
1.96988 1.952239
2.954819 2.928358
3.691554 3.658496
3
(t)=∆ h/m.cp
0.9801
1.98209
2.973134
3.76597
4
(t)= 0.0098Lsinα
0.98
1.96
2.94
3.67304
Calculation of Enthalpy from measured values and calculated values (Table -4) The value of change in enthalpy (∆H) sub segment wise calculated from measured data (Table-4) and enthalpy (∆Ha ) due to auto compression considering rise in temperature wet condition of shaft ( Table-5). The results are compared and percentage enthalpy due to auto compression are furnished in Table- (6) Table -6: Depicts auto compression effect in the shaft Air mass Sl-no Location ∆H= change flow in Specific (Kg/s)/ 100 enthalpy m (kJ/kg)/ 100m 87.717 2 100 m 2.17
]
∆Ha= Heat due to auto compression (kJ/kg) 1.029
Effect of auto compression in (%) on each section 47
Relative Humidity (%)
85.42
3
200 m
87.674
2.2
1.029
46
88.96
4
300 m
87.765
2.27
1.029
45
96.21
5
374.8 m (Pit No.2 – bottom)
87.225
6.97
1.16
17
96.22
The results from table (6) reveal that the effect of auto compression in the shaft at 100m, 200m, 300, and 374.8 m is 47 %, 46%,45% and17% respectively.. The corresponding value of relative humidity in sub segments are of the order of 85.42%, 88.96%, 96.21% and 96.22% respectively. The change in enthalpy due to auto compression is less in sub segment from 300m – 374.8m. This may be due to the seepage of water followed by conversation of heat to latent heat. Hence the results are corroborated with findings of other researcher [15].
8
5.1 FIELD OBSERVATION OF AUTO-COMPRESSION IN INCLINE OPENINGS: The value of temperature of intake air from Pit no.2 bottom to XI seam working, divided into six segments was calculated using equation (18). The results are furnished in table-7. TABLE – 7: Temperature rise in all the segments due to auto compression of air in inclined airways
Sl. No
1. 2. 3. 4. 5. 6.
Segment-no
sin α
Temp rise Addition of Specific due to auto heat due to enthalpy (kJ/kg) compression auto compression (kJ/kg)
Effect of Relative heat due to Humidity auto ( %) compression (%)
Segment-2 Segment -3 Segment 4 Segment -5 Segment-6 Segment -7
0.1031 0.0397 0.087 0.0378 0.03752 0.2323
0.656747 0.106915 0.153468 0.018522 0.1654632 0.6260405
30 28 29 20 15 5
0.689 0.11 0.162 0.02 0.173 0.658
2.3 0.39 0.55 0.1 1.23 13.1
96.31 96.31 96.34 96.34 94.54
12
97
10
96.5
8
96
6
95.5
4
95
2
94.5
0
94 0
500
1000
1500
2000
Relative humidity (%)
Graph showing the variation of relative humidity with specific enthalpy and heat due to auto compression in inclined roadways 97.5
14
Heat(kJ/kg)
97.03
Addition of heat due to auto compression (kJ/kg) Specific enthalpy (kJ/kg)
reiative humidity %
2500
Underground length(m) Figure -4: Gradient of specific enthalpy & heat due to auto compression and relative humidity from Pit No. 2 bottom to XI seam working with distance Figure depicts that total specific enthalpy due to addition of heat of auto compression is almost equal to the specific enthalpy as calculated by the formulas. In this case the specific sigma heat i.e. the dry heat obtained from the simulation of the field data is less than that of the specific enthalpy. This may be due to the evaporation of water.
5.2 Computer simulation of climatic condition of ventilation circuit The climatic condition of intake airways was simulated using software“PREDCLIM based on radial variation in temperature around the incremental length of airway[16] . In the software input parameters are: (i) area of crosssection, m2 , (ii) perimeter, m, (iii) airway length, m, (iv) depth from any assumed datum of inlet of airway, m, (v) depth from any assumed datum of outlet of airway(m), (vi) distance interval at which results are required, m, (vii)
9
thermal conductivity of the rock, W/mK, (viii) thermal diffusivity of the rock, m2/hr, (ix) friction factor in SI units, (x) average wetness of the airway in fraction , (xi) geothermic gradient, m/K, (xii) virgin rock temperature, deg . 0C, (xiii) dry bulb temperature of air, deg . 0C, (xiv) wet bulb temperature of air, deg. 0C, (xv) barometric pressure, kPa, (xvi) airflow rate, m3/s, (xvii) distance of heat source from airway inlet, m, (xviii) starting distance of linear heat source from airway inlet, m, (xix) running length of linear heat source, m, (xx) total sensible heat load, kW, (xxi) total latent heat load, kW. The values of parameter s segment wise were taken from table (1-3). The wet and dry bulb temperatures of air at the entry of the working ( XI seam by increasing overall air quantity in each segments by 40%. were predicted. The results are furnished in Table-9. Similarly, wet and dry bulb temperatures of air at the entry of the working ( XI seam by increasing overall air quantity in each segments by 40% with the value of heat due to auto compression as an additional heat source ( kW) in each segment ( table-5&6) were also predicted The results are furnished in Table-9. The required air quantity in the ventilation circuit was achieved by introducing Booster fan in main return. The result of investigation after installation of booster fan are also furnished in table-9
Table – 9: Result of simulation of ventilation circuit without considering auto compression SegmentPredicted Measured No Without considering Auto Considering Auto compression
Segment-2 Segment-3 Segment-4 Segment-5 Segment-6 Segment-7
compression Air dbt(0C) quantity (m3/s) 44.5 29.01 43.7 29.17 43.2 29.18 43.2 29.65 43 29.55 26.2 30.50
wbt(0C)
28.77 28.85 28.88 29.20 29.22 30.03
Air quantity (m3/s) 44.5 43.7 43.2 43.2 43 26.2
dbt(0C)
wbt(0C)
30.61 30.91 30.94 31.04 31.24 31.38
29.97 30.51 30.62 30.73 30.8 30.42
Air quantity (m3/s)
dbt(0C)
44 44 42 41 40 26
wbt(0C)
30.5 31 31.5 0.5 31.5 31.5
29.5 30.5 30.5 31 31 30.5
The following points are emerged from field investigation and computer simulation studies: 1. The ventilation circuit of length 2405 m comprising seven segments from surface to XI seam working at depth of 542.2m is taken into consideration in this study. 2. The addition of specific enthalpy due to auto compression in segment -1(Pit No.2; depth 374,8m) is measured of the order of 4.24 kJ/kg. This is about 31% of the total enthalpy (i.e. of the order of 13.61 kJ/kg). 3. The wet & dry bulb temperatures with air quantity 26.2 m3/s predicted by computer simulation studies without considering the effect of auto compression is of the order of 30.030c % 30.50c respectively. 4. The wet & dry bulb temperatures with air quantity 26.2 m3/s predicted by computer simulation studies considering the effect of auto compression is of the order of 30.420c % 31.380c respectively. 5. The wet & dry bulb temperatures with air quantity 26.0 m3/s measured is of the order of 30.50c % 31.50c respectively. 6. Hence the result of measurement of wet & dry bulb temperatures and the values predicted by computer simulation studies considering the effect of auto compression are almost same.
10
7. CONCLUSION From the results of investigation and computer simulation studies it may be concluded that for realistic estimation of air quantity requirement for deep mines (i.e. >300 m) consideration of heat due to auto compression is necessary.
8. Acknowledgements The authors would like to express their deep gratitude to AcSIR (Academy of Scientific and Innovative research) for providing the onsite training programme in mines, to the mine officials of no-2 pit of Jamadoba colliery, Tata Steel Ltd.
9. REFERENCES 1. 2. 3. 4. 5. 6.
7. 8. 9. 10. 11. 12. 13. 14. 15.
T.C 9.2 Industrial air conditioner, chapter-27, Mine air conditioning and ventilation, American society of heating, refrigeration and air conditioning engineers (ASHRAE-handbook), HVAC application,pp-27.2. Ramani R. V. (1992). Personnel Health and Safety, Chapter 11.1 SME Mining Engineering Hand Book, 2nd Edition Volume 1, H. L. Hartman Senior Editor, pp. 995 -1039. http://books.google.co.in/books/about/Mine_Ventilation_and_Air_Conditioning. Hartman, H L, Mutmansky, J M and Ramani, R V, 1997. Mine ventilation and air conditioning. New York: John Wiley. Banarjee, S.P, Auto compression of mine air, Chapter- 4, Mine Ventilation, Textbook, Lovely prakashan, Dhanbad, 1986, page- no- 127. Mishra, G.B, auto compression, chapter-iii, Mine environment and ventilation, textbook, Oxford University press publication, 1986, Pp-160-162. Vutukuri, V.S, Lama, R.D, Adiabatic compression, Chapter- 7, Environmental engineering in mines, Textbook, CAMBRIDGE UNIVERSITY PRESS, 1986, page-no- 217-218. Mishra, G.B, auto compression, chapter-iii, Mine environment and ventilation, textbook, Oxford University press publication, 1986, Pp-160-162. Banarjee, S.P, Auto compression of mine air, Chapter- 4, Mine Ventilation, Textbook, Lovely prakashan, Dhanbad, 1986, page- no- 127-128. T.C 9.2 Industrial air conditioner, chapter-27, Mine air conditioning and ventilation, American society of heating, refrigeration and air conditioning engineers (ASHRAE-handbook), HVAC application,pp-27.2. Navarro, Vidal F. Torres, Singh, N. Raghu, 2003, Thermal state and human comfort in underground mining, intech open publication, pp-592. Hartman .L Howard, Mutmansky, .M Jan, Ramani, R.V, Wang, Y.J Auto compression, Chapter – 16, Mine Ventilation and Air conditioning, Textbook, John Wiley & sons publication 1997,page-no -587. Navarro, Vidal F. Torres, Singh, N. Raghu, 2003, Thermal state and human comfort in underground mining, intech open publication, pp-595. Vutukuri, V.S, Lama, R.D, psychometrics of air-water vapour mixtures, appendix iii, Environmental engineering in mines, Textbook, Cambridge university press, 1986, page-no- 485. Navarro, Vidal F. Torres, Singh, N. Raghu, 2003, Thermal state and human comfort in underground mining, intech open publication, pp-595.
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