Question 2. A family in Eastern Australia installs solar panels to run an air-source heat pump to heat their swimming pool. The panels produce a total of around 6 kW of electricity during the day. The heat pump draws 5 kW of electricity and delivers 23 kW of heating to the pool.

a) The pool contains 40,000 litres of water. When the heat pump is running, estimate the rate at which the temperature of the water in the pool rises, in kelvins per hour. How much would the pool heat up after 8 hours of running the heat pump? Assume a specific heat capacity for the water of 4.18 kJ kg–1 K–1. [4 marks] Answers: 0.5 K per hour, 4 K

b) If the cost of electricity in that part of Australia is 0.25 $ per kWh, how much has the family saved by using solar power instead of purchasing electricity to heat the pool directly for 8 hours? [2 marks] Answer: $46

c) The additional 1 kW of electricity generated by the solar panels is available to run the centrifugal pump that pumps the water from the swimming pool through the heat pump (a negligible amount of this energy ends up as heat energy in the water; most is lost to the atmosphere). Figure 2.1 shows the characteristic curves for the pump at different speeds. The pump sits below the pool, with pipework totalling 11 m of 25.4 mm internal diameter smooth plastic piping. There is a sharp-edged inlet (KL = 0.5) and exit back into the pool (KL = 1.0), with two 90° bends (KL = 0.85 each) in the pipework on both the suction and discharge sides (four 90° bends altogether).

i) Write down the extended form of Bernoulli’s equation, including terms to account for the head loss due to friction and the head contributed by the pump. [3 marks]

ii) In this system the head loss due to friction must be just balanced by the pressure head increase delivered by the pump. Show that the head loss due to friction can be expressed as a function of the volumetric flowrate of fluid through the pump, Q, as follows: 2 ?h f ? 20 00 00KQ [6 marks]

iii) For a flowrate of 120 litres min–1, use the Moody chart on page 3 to show that the Fanning friction factor is around 0.0044, and show that the head loss due to friction is 10 m. Assume the density of water is 1000 kg m–3 and the viscosity is 0.001 Pa s. [10 marks]

iv) From the characteristic curves shown in Figure 2.1, identify the pump speed in rpm required to deliver the desired flowrate of 120 litres min–1. Explain your reasoning. [2 marks] Answer: 2000 rpm

v) Calculate the power drawn by the pump to deliver 120 litres min–1, if the pump efficiency is 65%. [3 marks] Answer: 300 W

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Design of Shell and Tube Heat Exchanger

Crude oil at 198°C is to be cooled to 39°C. The oil flow-rate is
6.127 kg/s. Cooling water

is available at 29°C and at the rate of 27.127 kg/s. The pressure
drop allowance for each stream

is 100 kN/m2

. Design a suitable shell and tube heat exchanger for this
duty.

The following are the properties of the two streams at the average
temperature:

water | crude oil | |

density kg/m3 | 990 | 850 |

viscosity mNm-2 s |
0.680 | 0.18 |

thermal conductivity W/m K | 0.630 | 0.130 |

specific heat kJ/ kg °K | 4.2 | 2.3 |

Data:

Assume overall heat transfer coefficient of 502 W/m2 K.

Tubes: 20 mm o.d., 16 mm i.d. tubes, 4 m long, square pitch 1.25do,
carbon steel.

Pull through head, Floating Head type heat exchanger.

Baffle = 1/5 of the shell diameter and 25 % cut baffles

Fouling factors 0.0003 m2 K/ W for cooling water and 0.0002 m2 K/ W
for crude oil

Thermal conductivity of metal = 57 W/m K

Present your results with detailed calculations to design Shell and Tube Heat Exchanger. Mention the various assumptions made in the calculations.

Estimate the cost of the heat exchanger.

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Define (i.e. physical meaning) SRT, HRT, F/M ratio, SVI and indicate their importance during the operation of an activated sludge process in wastewater treatment plants.

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Q1. What is the dominant form of benzoic acid at pH 2. Suggest the dominant form of caffeine at pH 2.

Q2. This lab uses a C18-reverse phase column. What does the stationary phase consists of? Is it polar or nonpolar?

Q3. Predict whether benzoic acid or caffeine will come out of the C18-reverse phase column first at pH 2.

Q4. To prepare the calibration standard solutions, calculate how much of each stock solution of sodium benzoate and caffeine should be added to each of the 25 mL volumetric flasks (See the procedure).

Q5. What are the peak absorption wavelengths of sodium benzoate and caffeine, respectively?

In: Other

Describe the process of carbon dioxide absorption by a named solvent in a plate tower.

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For IEUBK Model) 1.What assumptions are made when using this type of model? That is what values or relationships must the model include, which you did not supply. 2.What are the model supplied (“fixed") parameters which are assumed? 3.What are the user-supplied input variables required to run the model?

In: Other

**Discuss a number of waste removal/ disposal methods for
chlorinated hydrocarbon solvents in the petrochemical
industry**

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A gasoline storage tank drains by gravity to a tank truck; see the drawing. The pipe line between the tank and the truck is 100 m of 0.1 m diameter commercial steel pipe. The properties of gasoline are given as, density=720 kg/m3, dynamic viscosity = 0.0006 kg/m.s. Both tank and truck are open to the atmosphere, and the level in the tank is 10 m above the level in the truck. What is the volumetric flow rate of the gasoline? and how we choose moody chart

In: Other

A gasoline storage tank drains by gravity to a tank truck; see the drawing. The pipe line between the tank and the truck is 100 m of 0.1 m diameter commercial steel pipe. The properties of gasoline are given as, density=720 kg/m3, dynamic viscosity = 0.0006 kg/m.s. Both tank and truck are open to the atmosphere, and the level in the tank is 10 m above the level in the truck. What is the volumetric flow rate of the gasoline? and how we choose moody chart

In: Other

What types of analytes can be analyzed using gas chromatography? What types of analytes are unsuitable for analysis with this technique? Which would be expected to elute first on a polydimethyl sioxane column, butane, or butanol? Why? What factors determine relative retention time with gas chromatography?

What is the basis for separation in gas chromatography? (I.e. adsorption, partition, size exclusion, ion exchange, or affinity?)

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1. A gas mixture containing a solute with a concentration of
Y_{1}=0.02 to be absorbed in a packed tower. The gas-liquid
equilibrium is described by: Y^{*}=1.0X.

(a) (10%) To achieve a 99% solute
recovery, calculate the required gas phase overall mass transfer
unit N_{tOG} and the composition X_{1} at the
liquid exit. X_{2}=0.0001 at the liquid inlet with
L/G=1.2.

(b) (10%) For pure liquid inlet with L/G=0.8, what is the maximum percentage solute recovery?

2. For a packed tower for gas absorption operation, under a given operating condition, it is found that kya=kxa=0.026 kmol/m2.s. The equilibrium equation is given by: y=5x. Given that ky?G0.8, calculate the percentage reduction in overall mass transfer coefficient if the gas flow rate is doubled while the liquid flow rate remains unchanged.

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Describe three techniques for “perpetual storage” of hazardous wastes. If you had to make a decision among the three techniques for disposing of dioxin-contaminated waste, would you be able to recommend one?

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500 kmol/h of an air stream at a pressure of 2 atm is to be heated from 15 celsius to 90 celsius in a heat exchanger with 600 kPa steam condensing in the shell side of the heat exchanger. Steam enters the exchanger as a saturated vapor and leaves as a saturated liquid.

A) How much steam would be required if a conventional heat
exchanger were used? what is the total entropy change during this
process?

B) How much steam would be required if the process of heating the
air was carried out by using the heat transferred from the steam to
drive a reversible carnot engine and by using the air stream as the
heat sink? what would be the total work output of this engine?

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An air stream at 87.8°C having a humidity H = 0.030 kg H2O/kg dry air is contacted in an adiabatic saturator with water. It is cooled and humidified to 90% saturation. (a) What are the final values of H and T? (b) For 100% saturation, what would be H and T?

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Air entering a dryer has a temperature (dry bulb) of 60°C and a dew point of 26.7°C. Using the humidity chart, determine the actual humidity H, percentage humidity HP, humid heat cS and humid volume vH.

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