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MindTap for Herman's Understanding Motor Controls, 4th Edition [Instant Access], 2 terms
4th Edition
ISBN: 9781337798754
Author: Herman; Stephen L.
Publisher: Cengage Learning US
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Question
Chapter 1, Problem 7RQ
To determine
The most common method of controlling the speed of an alternating current motor.
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give me solution math not explin
give me solution math not explin
use
Q
Strips of material 10 mm thick are dried
under constant drying conditions from
28 to 13 per
cent moisture in 25 ks. The equilibrium
moisture content is 7 per cent. The
relation between
E, the ratio of the final free moisture
content at time t to the initial free
moisture content, and
the parameter J is given by:
E
1
0.64
0.49
0.38
0.295
0.22
0.14
J
0
0.1
0.2
0.3
0.5
0.6
العنوان
0.7
It may be noted that J = kt/12, where, k =
constant, t = time (ks) 1 = thickness/2 of
the sheet of
material (mm)
a. Based on the given data, plot a graph
of E against J
b. Determine the time taken to dry
60 mm planks from 22 to 10 per cent
moisture under the
same conditions assuming no loss from
the edges?
ina östler
۲/۱
Chapter 1 Solutions
MindTap for Herman's Understanding Motor Controls, 4th Edition [Instant Access], 2 terms
Ch. 1 - When installing a motor control system, list four...Ch. 1 - Prob. 2RQCh. 1 - Is the National Electrical Code a law?Ch. 1 - Explain the difference between manual control,...Ch. 1 - Prob. 5RQCh. 1 - Explain the difference between jogging and...Ch. 1 - Prob. 7RQCh. 1 - What agency requires employers to provide a...Ch. 1 - What is meant by the term ramping?
Ch. 1 - What is the most important function of any control...
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- 14.25.2.5 kg/s of a solution at 288 K containing 10 per cent of dissolved solids is fed to a forward-feed double-effect evaporator, operating at 14 kN/m² in the last effect. If the product is to consist of a liquid containing 50 per cent by mass of dissolved solids and dry saturated steam is fed to the steam coils, what PROBLEMS 1179 should be the pressure of the steam? The surface in each effect is 50 m² and the coefficients for heat transfer in the first and second effects are 2.8 and 1.7 kW/ m² K, respectively. It may be assumed that the concentrated solution exhibits a boiling-point rise of 5 deg K, that the latent heat has a constant value of 2260 kJ/kg and that the specific heat capacity of the liquid stream is constant at 3.75 kJ/kg K Oarrow_forward: +0 العنوان use only 5) A 100 kg batch of granular solids containing 30% moisture is to be dried in a tray drier to 15.5% by passing a current of air at 350 K tangentially across its surface at a velocity of 1.8 m/s. If the constant rate of drying under these conditions is 0.7 g/s m2 and the critical moisture content is 15%, calculate the approximate drying time. Assume the drying surface to be 0.03 m2 /kg dry mass. мониarrow_forwardgive me solution math not explinarrow_forward
- ۲/۱ : +0 العنوان seoni 4) 1 Mg (dry weight) of a non-porous solid is dried under constant drying conditions with an air velocity of 0.75 m/s parallel to the drying surface. The area of drying surface is 55 m2 If initial rate of drying is 0.3 g/m2 s, how long it will take to dry a material from 0.15 to 0.025 kg water/kg dry solid? The critical moisture content is 0.125 and the equilibrium moisture is negligible. The falling rate of drying is linear in moisture content. If air velocity increases to 4 m/s, what will be the anticipated saving in drying time? 0 ostherarrow_forward14.23. A double-effect forward-feed evaporator is required to give a product consisting of 30 per cent crystals and a mother liquor containing 40 per cent by mass of dissolved solids. Heat transfer coefficients are 2.8 and 1.7 kW/m² K in the first and second effects respectively. Dry saturated steam is supplied at 375 kN/m² and the condenser operates at 13.5 kN/ m². (a) What area of heating surface is required in each effect assuming the effects are identical, if the feed rate is 0.6 kg/s of liquor, containing 20 per cent by mass of dissolved solids, and the feed temperature is 313 K? (b) What is the pressure above the boiling liquid in the first effect? The specific heat capacity may be taken as constant at 4.18 kJ/kg K. and the effects of boiling-point rise and of hydrostatic head may be neglected. O Oarrow_forward5) A 100 kg batch of granular solids containing 30% moisture is to be dried in a tray drier to 15.5% by passing a current of air at 350 K tangentially across its surface at a velocity of 1.8 m/s. If the constant rate of drying under these conditions is 0.7 g/s m2 and the critical moisture content is 15%, calculate the approximate drying time. Assume the drying surface to be 0.03 m2 /kg dry mass. Oarrow_forward
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- 14.9. A forward feed double-effect vertical evaporator, with equal heating areas in each effect, is fed with 5 kg/s of a liquor of specific heat capacity of 4.18 kJ/kg K. and with no boiling point rise, so that 50 per cent of the feed liquor is evaporated. The overall heat transfer coefficient in the second effect is 75 per cent of that in the first effect. Steam is fed at 395 K and the boiling point in the second effect is 373 K. The feed is heated by an external heater to the boiling point in the first effect. It is decided to bleed off 0.25 kg/s of vapour from the vapour line to the second effect for use in another process. If the feed is still heated to the boiling point of the first effect by external means, what will be the change in steam consumption of the evaporator unit? For the purpose of calculation, the latent heat of the vapours and of the steam may both be taken as 2230 kJ/kg Ад Oarrow_forwardcorrect the shaft misalignment in a cars transmission system, determine the offset distance required to correct the shaft misalignment of 4 degrees in a rotating system. shaft diameter is 4cm.arrow_forward14.14. A three-stage evaporator is fed with 1.25 kg/s of a liquor which is concentrated from 10 to 40 per cent solids by mass. The heat transfer coefficients may be taken as 3.1, 2.5 and 1.7 kW/m² K, respectively, in each effect. Calculate the steam flow at 170 kN/m² and the temperature distribution in the three effects, if: (a) the feed is at 294 K, and (b) the feed is at 355 K. Forward feed is used in each case and the values of U are the same for the two systems. The boiling point in the third effect is 325 K and the liquor has no boiling point rise. Oarrow_forward
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