• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

To determine the effect of flowrate on rate of heat transfer.

Extracts from this document...

Introduction

OBJECTIVE: To determine the effect of flowrate on rate of heat transfer INTRODUCTION: A concentric tube or double pipe heat exchanger is one that is composed of two circular tubes. One fluid flows in the inner tube, while the other fluid flows in the annular space between the two tubes. In counter flow, the two fluids flow in parallel, but opposite directions. In parallel-flow the two fluids flow in parallel and in the same direction. Fig. (1) PROCEDURE: The work was carried out the lower exchanger of a pair of concentric tube heat exchange. The lower exchanger had water passing through the inner tube, being heated by steam which flows into the outer tube and condenses. The condensate usually returns to the steam boiler, but there was a sampling facility so it may be collected and timed to determine condensate flowrate. The water to the lower exchanger was turned on and the flow was set to the desired rate. The condensate return line was checked if it was open to drain (floor),then the stem was turned on to the lower exchanger and the pressure was set at 10 psig. ...read more.

Middle

(Tc out - Tc in) .................................... (1) For the steam side: Qh =mh.?v+mh.Cph. (Ts-Th out) ............................... (2) Where mh can be calculated from mh = Fh* ?c And mc = Fc * ?c Symbols:- Cpc= specific heat capacity of cold water, J/kg.K Cph= specific heat capacity of hot condensate, J/chg. Fc = volumetric flowrate of cold water, m3/s Fh = volumetric flowrate of hot condensate, m3/s mc = mass flowrate of cold water, kg/s mh = mass flowrate of hot condensate, kg/s Qc = energy gained by cold water, J/s Qh = energy lost by steam, J/s Tc in = temperature of cold water entering Ts = temperature of steam entering exchanger, K Th out = temperature of hot condensate leaving exchanger, K ?v = latent heat of vaporisation of steam, J/kg ?c = density of cold water, kg/m3 ?h = density of hot condensate, kg/m3 RESULTS: The results which took in the laboratory: Runs Cold water flowrate (Litters/min) Steam in temp. Steam out temp. Could water in temp.(C) Could water out temp.(C) Condensate flowrate (millilitres/min) 1 17 113 112 0.7 41 1800 1840 2 2 113 112 0.7 84 1280 3600 3 15 113 112 0.7 41 2040 1680 4 5 112 111 0.7 63 1360 1280 5 10 113 112 0.7 48 1440 1566 CALCULATION: Note: Conversion: (Litters/min) ...read more.

Conclusion

Example: (I used the first run in this example): Fc = 17 * (0.001/60) = 0.000283 (m3/s) mc=0.000283 * 996= 0.2822 kg/s Qc =0.2822 * 4180 (314 - 280) = 40106.26 J/s * To worked out the value of Qh we used equation (2), but we had first to got the value of mh from this equation: mh = Fh* ?c To get value of Fh we took the average of the condensate floweate values and then we converted it from (millilitres/min) to (m3/s). Example: (I used the first run in this example): Fh = (1800+1840)/2 * (0.000001/60) = 3.03333E-05(m3/s) mh=3.03333E-05 * 958 = 0.029059333 kg/s Qh = 0.029059333*2.22 * 106 + 0.029059333 * 996 (386 - 385) =64634.35 J/s DISSCUSSING THE RESULT& CONCOLUTION: * When the flowrate is increased the % difference between the energy lost by steam and the energy gained by cold water will decrease. * The relation between Qc and Fc is direct proportion, therefore to transfer heat faster, we must increase the flowrate. * The value of the % difference in the first run is 125.7, which I think it is wrong and that happened because the flowarete value was too small, and that make the value of Qc small as well, therefore the difference is high. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Green Plants as Organisms section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Green Plants as Organisms essays

  1. My investigation is to find out the rate of which heat transfer happens. Heat ...

    If the container has a larger surface area it can result in more heat loss as the bigger the surface area the quicker evaporation can take place. Evaporation is the change of water in to a gas, steam, which will then rise into the air.

  2. Thermal Energy Transfer

    This process can also be called the Wave Motion. When the volume of water is higher, it will stay warmer for longer than if there was a low volume of water. This is because when there is a high volume of water then the outside of the water will cool

  1. Study the condensation of steam at different temperature levels

    * As the balances I am using are electronic, subjecting them to steam is not the best idea as I will soon find myself in a rather large debt to the physics department in school, also another thing against this idea is that steam will collect on the balance plate as it is steel and will obviously be cold.

  2. Investigation into the relationship between the density of fresh water shrimps in fleet brook ...

    The water temperature is monitored at every site. This again ensures that the temperature of the water is constant throughout every site. The water of the brook should be of very similar temperatures since the flowing water currents will distribute the heat evenly throughout the river.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work