Gujarat University 2009-8th Sem B.E Mechanical Engineering Airconditioning Engineering, , , Gujrat University - Question Paper

B.E. (Mech.) Sem. VIII

June - 2009 EP-II - Airconditioning Engineering

Time: 3 Hours]    [Max. Marks: 100

Instructions : (1)    Attempt all questions.

(2)    Figures to the right indicate full marks.

(3)    Assume suitable additional data if necessary.

(4)    Use of calculator, charts and table is permitted.

1.    Explain factors governing By-pass factor.    18 A department store has the following data:

Room sensible heat load = 64 kW

Room latent heat load =16 kW

Room design condition 24 C DBT & 50% RH

Outside design condition 35 C DBT & 24 C WBT

Ventilation air required is 100 m³/min and coil by-pass factor is 0.15.

Plot a psychrometric chart and calculate

(a)    Outdoor air load

(b)    Grand total heat

(c)    Effective sensible heat factor

(d)    Coil ADP

(e)    Dehumidified air quantity

(f)    Room sensible heat factor

(g)    Entering and leaving condition of air at the apparatus

2.    (a) What is flywheel effect as applied to load calculation ? How it is useful ?    16 (b) What do you understand by term SHGF ? How will you estimate the value of

SHGF for different orientation, month and time ?

OR

(b) Calculate ICL and IHG for a 10 m² window having inside venetial blinds as shading device situated in NW wall in Ahmedabad city in the month of 21^st June.

3.    (a) What is a comfort zone ? What are the physiological-bed effect of hot and cold

extremes ?    16

OR

Explain humidity and its importance for human and industrial air conditioning. Explain humidification control in Air washer.

(b) Role of thermostats and humidifiers in Air conditioning system.

OR

What is ventilation ? How it differs from infiltration ?

(a)    What is the difference between a fan and blower ? Explain construction and working of a Tube Axial Fan.    16

(b)    What do you understand by non-overloading characteristics of a fan ? Which fan takes over load while working in the plant ?

OR

(b) A fan delivers 9000 lit/sec of standard air at a pressure of700 Pa. at a fan speed of 450 ipm and a power input of 13 kW. What speed, input power and static pressure are required if the flow rate is increased to 13000 lit/sec. by increasing the rotational speed ?

(a)    Explain the terms Aspect Ratio and Attic Air.    16

(b)    Derive an expression for equal diameter of circular duct for a rectangular duct, where flow rate in both ducts is same.

(c)    Explain static pressure, velocity pressure and total pressure of air flowing in a duct ? How above pressures are measured by using a pitot tube in your laboratory ?

OR

(a)    What is AHU ? How it differs from FCU ?

(b)    What are the requirements of a good air distribution system ?

(c)    A packaged Air conditioning plant serves four rooms in an apartment. The schematic layout of the duct system together with volume flow rate to each room is shown in Fig. (given below). The lengths of the duct sections are listed in table. Design the duct sizes using the equal friction method using charts and tables. Attach the chart with your answer book. The air velocity in the first section is not to exceed 8 m/sec.

Section	A-B	B-C	C-D	D-E	B-H	C-G	D-F
Length in m.	2	4	4	8	7	3	2

Write short note (any three):

(a)    Split Air conditioning unit.

(b)    Face and By-pass damper control.

(c)    Dynamic losses in duct design.

(d)    Construction and working of Anemometer.

(e)    Desert cooler.

Flow Rate m7s
0.1 0.2 0.4 0.6 0.8 1 1.5 2 3 4 6 8 10 15 20 30 50 100 Friction Loss. Pa/m

Table Z Circular Kquivalents of RecUngular Duct for Equal Friction nd Opacity* Uiiglii Unt SMc of Rietmgular Ouct (a), row

100	10V
125	122	137
50	<33	1M>	164
17}	143	ifl	177	191
200	IK	112	189	204	219
225	161	ISt	200	216	232	2'6
250	169	190	210	228	244	259	273
171	176	199	220	238	Z16.	272	287	301
300	183	207	229	248	266	283	299	314	328
310	195	222	245	267	2R6	305	322	339	354	383	437
400	107	233	260	283	301	325	343	361	378	409
410	317	247	274	299	321	343	363	382	400	433	464	492	&
500	227	218	287	313	337	360	381	401	420	455	488	SIS		601
110	236	260	299	326	352	375	398	419	439	47?	Sit	543	573		656
600	2->l	79	3:8	339	365	390	414	436	457	496	533	567	598	628				.
610	213	249	321	311	378	404	429	412	474	515	553	St.)	622	653	683	711	76}
700	261	298	331	362	391	413	443	467	490	533	573	610	644	677	708	737		820
710	26S	306	34)	373	402	4 JO	417	482	506	550	591	630	666	700	732	763	792		75
soo	275	314	310	383	414	442	470	496	320	167	609	649	687	722	715	787	818	*47
900	229	330	367	402	435	4&1	494	522	548	597	"643	686	726	763	799	833		*97	927	9M
lews'	301	344	3X4	420	454	436 .	517	146	574	626	674-	719	762	802	840	M6	911	944'	926	1037
1100	313	35*	3S9	437	47}	106	538	569	598	612	703	751	795	838	87J.	.<1)6	953	98S	1022	I0U
1203.	324	.370.	.413.	413	..490	. 525	518 .	190	620	677 ,	...?3I	780	827	872	9)4	95*	s;j	icxv	1066	U?>
1303	334.	.382.	426..	.468.	. 106.	143	57?	610	642 .	.701	751	. SOS	. 857	904	948	990	1031	1069	1107	1177
1400	3	394	439	482	122	159	595	62'	662	724	781	835	886	934	980	|U2i	1066	1107	1146	IIS
1100	313	404	412	491	136	175	612	648	681	745	05	860	913	963	1011	1057	(ICC	1143	1183	1260
1600	362	411	463	50$	;n..	' 191	629	665	700	766	827	885	39	991	1041	1088	1133	1177	1219	INI
1700	371	421	475	521	564	605	6M	682	718	785	849	903	964	1018	1069	1119	It6	12C9	1213	1335
1S00	379	<34	481	133	177	619	660	60S	731	804	869	930	988	1043	1096	IU6.	1195	1241	1286	1371
1900	3S7	444	496	144	V	(63	674	713	711	823	889	912	1012	106S	M22	1174	1221	1271	lilt	(40$
000	395	<33	106	IIS	602	646	&SS	728	767	840	90S	V)	1034	1092	1147	1200	121!	1301	134*	14.18
2100	402	461	516	266	6I	619	702	74}	752	*57	927	993	1051	11)1	1172	1226	1279	1329	7t	1470
2230	410	470	525	577	625	671	711	757	797	874	945	1013	1076	1)37	1195	1251	1305	1316	1401	ilu;
2300	417	47K	13*	587	636	68J	728	7/1	812	890	963	1031	1097	1159	ISIS	1171	133)	1333	1434	iu:
2400	424	426	543	597	647	695	740	7*4	826	901	980	1010	1116	1180	1241	1299	1311	1409	1461	ISM
2100	430	194	112	606	658	706	7J3	797	S40	920	996	106S	1136	J200	1262	1333	1379	1434	1483	IJW
2600	437	SOI	560	616	668	717	764	810	813	935	1011	1085	>154	1220	1283	1344	!402	1459	1513	1617
2703	443	109	169	625	678	73	776	822	566	950	1028	1102	1173	1240	1304	1366	1421	1483	1538	IfrU
J&C0	410	116	<77	634	68$	738	787	334	879	964	1043	1119	1190	1259	1324	1387	1447	1506	1562	I67U
2900	456	?23	W5	6*3	697	749	798	*41	891	977	!05<	1135	1208	1277	1344	1401	14 .	1529	1186	lulfcr

Ltnglh Ont Sid* of RrtUngultr Duel (a), mm

_ . 1000 1100 1100 1300 1400 1500 1(00 1700 1800 1900 2000 1100 2100 3300 3400 1100 HOP 1700 M00 2W> IfZlO     ........... 1,1 -    ' 1 CircuUr Duct Dluwtef. row___
1000 IW3 1100 l!46 1202 1200 1196 1256 1312 1300 1244 1306 1365 142) 1*00 1289 1354 14(6 1475 113U 1100 1332 1400 1464 1526 1584 IMO 1600 1373 1444 1511 1574 1635 1693 1749 1700 1413 1486 1555 1621 1634 1745 1803 181* ISOi) MSI 1527 1598 1667 1732 (794 1854 1912 1968 1900 1488 1566 1640 1710 1778 1842 1904 1964 2021 2077 2000 1123 1604 1680 1753 I8>2 1889 1952 2014 2073 2131 2186' 2100 1518 1640 1719 1793 1865 t933 1999 2063 2124 2183 2240 2296 2200 1191- 1676 1756 1833 1906 1977 2044 2)10 2173 2233 2292 2350 2405 2300 1623 1710 1793 1871 1947 2019 2088 2155 2220 2283 2343 2402 2459 2514 2400 1655 1744 1828 1909 1986 2060 2131 2200 2266 2330 2393 2453 2511 2S68 2100 1681 1776 1862 194$ 2024 2100 2173 2243 2311 2377 2441 2502 2562 2621 2600 1715 1808 1896 1980 2061 2139 2213 2285 2355 2422 2487 2551 2612 2672 2700 1744 IS39 1929 2015 2097 2I7T 2253 2327 2398 2466 2533 2598 2661 2722 2200 1772 '.869 1961 2048 2133 2214 2292 2367 2439 2510 2578 2644 2708 2771 2900 1800 1898 1992 2081 2167 2250 2329 2406 2480 2552 2621 2689 2755 2819	2881 2941 3001 305* 311#
TM* tutd anB,    *Lcn{il> i)>ccmtiit of mtvtfulx 4uct 'H nun.

Table No. 1 : % Section Area in branches for roaintainiug Equal Fraction

Capacity piVnurt ft Duct Area % % Capa. roVmin % Duet Area rr. /O Capa. m3/m % Duel Area % Capa. m3/m %. Duct Area % Capa. m3/m % Duel Area % Capa. mVm % Duel Area 1 Capa. mJ/m ft Duct Area * Capa. mJ/m % Duct Area % Capa. rn5/ra % Djci Area I 0 90 12 18.5 23 30.5 34 42.0 45 53 56 '64 67 73.5 78 83 89 91.5 2 3.5 13 19.5 24 31.5 35 43.0 46 54 57 65 68 74.5 79 84 90 92 j 5.5 14 20.5 25 32.5 36 44.0 47 55 58 65.5 69 75.5 80 84.5 91 93 4 7.0 15 21.5 26 33.5 37 45.0 43 56 59 , 66.5- 70 76.5 81 85.5 92 94 -.5 9.0 >6 23.0 27 34.5 38 46 49 57 '60* 67.5 71 77.0 82 86 93 94.5 6 10.5 17 24.0 28 3SJ 39 47 . 50 58 08 72 78.0 83 87 94' 95 7 l\S 18 25.0 29 3 6.5 40 48. 51 59 69 73 79 84 87.5 95 96 8 13.0 19 26.0 30 yijs 41 49 52 60 63 70 74 80 85 88.5 96 96.5 9 14.5 20 27.0 31 39.0 42 50 53 61 64 71 75 80.5 86 88.5 97 97.5 .to 16.5 21 . 28.0 32 4ao 43 51 54 62 65 71.5 76 81 87 90 98 9S 11 17.5 22 29.5 J3 41,0 44 52 55 63 66 72.5* 77 *2 88 90.5 99 99 1 . . 100 100

SOURCE ; Hand Book of Air Coaditiontag System Design-Carrier Corpoition 1965

Attachment: gujarat-university-2009-b-e-mechanical-engineering-33393-1.pdf

Earning:   Approval pending.