Challenges Of Vertical Heat Exchange Network Development In Chemical Engineering

Amazing Essays
THE UNIVERSITY OF MANCHESTSER
SCHOOL OF CHEMICAL ENGINEERING AND ANALYTICAL SCIENCES
CAPD Coursework 2

Zhibek Makhtayeva 9795616

Introduction

In the world with increasing demand of energy, it becomes more important to optimize the existing energy and utility systems. For example, heat exchange network development from the embryonic stage or retrofit of current systems are one of the challenges of chemical engineering nowadays. Heat exchange network design might have various objective functions, such as minimum utility costs, minimum investment costs or minimization of the number of possible matches in the configuration. To address these challenges, optimisation tools and techniques can be applied. The problem needs to be decomposed
…show more content…
There are 11 heat exchangers. Several streams are splitted, except hot stream 2 and cooling water. The total area of heat exchangers is 494.366 m2.

Figure 5. Heat exchange network (vertical heat transfer)
Slack variables were calculated by GAMS, the values can be found in Table 3. As it can be observed, values are small, but it is essential to add slack variables in order to optimise the objective function in GAMS.

Table 3. Values of slack variables
〖S1〗_(i,k)
0 kW 〖S2〗_(i,k)
0.004 kW 〖S3〗_(j,k)
0 kW 〖S4〗_(j,k)
0.004 kW
The heat loads of 11 heat exchangers are shown in Table 4. As it was mentioned in Introduction section, Qhot oil= 15 kW, Qcooling water = 534 kW (SPRINT results) for vertical heat exchange should be the same, because utilities and temperature boundaries of the blocks remain constant.

Table 4. Heat loads of generated heat exchange matches Block 1 (kW) Block 2 (kW) Block 3 (kW)
H1. C1 37.244
H1.C2 254.760
H1.C3 271.996 44.000 4.000
H1.QW 15.000
H2.C1 42.756
H2.C2 277.240
H2.C3 40.000
QS.C1 519.996
QS.C3 14.004
QW – cooling water, QS – hot oil

b) Criss-cross heat
…show more content…
Criss-cross heat transfer has one more heat exchanger, but the heat load on it is 0.004 kW, whereas the heat loads on both utilities increase by 0.004 kW. The areas do not differ significantly , the difference is 4.104 m2 , which is generated due to the additional heat exchanger. Moreover, for criss-cross heat transfer, heat recovery is 971.996 kW, which is a lower value than for vertical heat transfer, because slack variables were compensated by the use of utilities. Therofore, the total utility cost is approximately the same, whereas the annualised capital cost difference is about 300 $/yr. The heat load compensated by utilities in the basence of slack variables can be considered as a round-off and added to constraint equation of energy balances of hot and cold streams. In that case, both types of heat transfer models will have the same design, which means that the vertical heat transfer model is the optimal solution for the minimisation of total annualised cost. Moreover, the most contribution comes from the minimisation of utilities, taking into consideration that heat transfer was allowed across the

Related Documents

  • Decent Essays

    Heat Exchanger Analysis

    • 1505 Words
    • 7 Pages

    The heat exchanger design is an optimization engineering problem, to approach the best solution for sizing and selection of a heat exchanger and also to analyze its thermal performance. A properly sized heat exchanger should incorporate excess capacity to account for fouling that will occur during operation but too much oversizing results in higher manufacturing and installation costs. The most appropriate metric to describe the performance of a heat exchanger is its thermal capacity, which is its ability to transfer heat between the hot and cold fluids at different temperatures. Thermal capacity depends on the design of the heat exchanger unit and the fluid properties that flow in the device. If the heat transfer surface is sufficient, the…

    • 1505 Words
    • 7 Pages
    Decent Essays
  • Decent Essays

    The average heat transfer coefficient for without notched fin is 8.3887 W/m2K whereas for 20% notched fins it is 9.8139 W/m2K. Also the copper gives more heat transfer rate than aluminum plate. Copper plate gives better heat transfer rate than aluminum plate. S. M. Wange, R. M. Metkar did “Computational Analysis of Inverted Notched Fin Arrays Dissipating Heat by Natural Convection” [8]. Experimentation is done for four different cases of inverted notch fin arrays.…

    • 1203 Words
    • 5 Pages
    Decent Essays
  • Decent Essays

    The thermal efficiency is defined by the relation For analyzing the Rankine cycle, it is helpful to think of efficiency as depending on the average temperature at which heat is supplied and the average temperature at which heat is rejected. Any changes that increase the average temperature at which heat is supplied or decrease the average temperature heat is rejected will increase the Rankine-cycle efficiency. In analyzing the ideal cycles in this chapter, the changes in kinetic and potential energies from one point in the cycle to another are neglected. In general, this is a reasonable assumption for the actual…

    • 766 Words
    • 4 Pages
    Decent Essays
  • Decent Essays

    Thermal Equilibrium Essay

    • 3451 Words
    • 14 Pages

    What does specific heat 4 200 J of heat needs to be supplied to 1 of water 4 200 J kg-1°C-1 kg of water to produce a 1 °C temperature mean? increase. 6. The physical When two objects of equal mass are heated at meaning of equal rates, the object with the smaller specific specific heat heat capacity will have a faster temperature. capacity, c When two objects of equal mass are left to cool down, the temperature of the object with smaller heat capacity will drop faster.…

    • 3451 Words
    • 14 Pages
    Decent Essays
  • Decent Essays

    The plots for GAT, AGAT and DAGAT were straight lines, and the standard deviations were almost 1 for each, which indicate the independency of the thermal degradation of the energetic materials at various heating rates. However, the standard deviation for AZT was slightly less than that of the others. (27), (33), (40) The slopes of the lines equal for each material -Ea /R (2) through transposing Eq (2) The activation energy was found from the following equation E = 8.314 * slope (3) The activation energy values were later used for computing the pre-exponential factors (A) by equation (1). In the meantime, activation energies (Ea) for these energetic compounds were calculated by the Ozawa method. The Ozawa equation according to ASTM E698 is equal to the following…

    • 1161 Words
    • 5 Pages
    Decent Essays
  • Decent Essays

    1.4. Trihalomethanes 2. Ezbet El Moraba and Al Manshyia well water treatment plants 2.1. Physicochemical parameters Comparison between different physico chemical parameters was illustrated in table (6) and figures (15,16,17). The mean value of residual chlorine in Ezbet El Moraba well water treatment plant was 0.03 mg/L, while that of Al Manshyia well water treatment plant was 0.14 mg/L.…

    • 1719 Words
    • 7 Pages
    Decent Essays
  • Decent Essays

    3 (a) and (b), MA showed slightly better performance than EA on the extractor, MA produced high HAc flow rate in the extract stream with the same amount of MA and EA input on solvent stream. Especially, in the PX+MA system, while PX input on the solvent stream below around 1,000 kg/hr, only single phase take place in this system which means no separation occurs in the extraction…

    • 1263 Words
    • 6 Pages
    Decent Essays
  • Decent Essays

    Heat Release Rate Model

    • 836 Words
    • 4 Pages

    The gross heat release rate is synthesized with an equation (3) having two separate Wiebe efficiency factors ap and ad in the two Wiebe functions often referred to as double Wiebe function [25, 33]. The direct experimental measurement of heat release rate is difficult. Therefore, a net apparent heat release rate calculated from the experimentally measured pressure-time profile and computationally calculated piston displacement profile along with heat loss to the cylinder wall using equation (1) is applied for validation. The diesel and DME oxidation reaction equations assuming complete…

    • 836 Words
    • 4 Pages
    Decent Essays
  • Decent Essays

    For this purpose, the condensation of benzaldehyde (1 mmol) with dimedone (2 mmol) (Scheme 3) was optimized in terms of the catalyst amount and temperature, under solvent-free conditions; the results are summarized in Table 5. The logical results were obtained when 15 mol% of tartaric acid was utilized at 70°C (Table 5, entry 4). In another study, when the reaction was carried out at 80ºC, the product was obtained in 92% yield at 10 min in comparison with 70ºC (Table 5, entry 8). Nevertheless, 70ºC was selected as optimal reaction temperature, because one aim of this work was performing the reaction in milder reaction conditions with respect to the reported works, and this was more logical. The efficiency and the generality of the catalyst were examined by the reaction of different arylaldehydes (having electron-withdrawing substituents, electrondonating substituents) with dimedone.…

    • 1155 Words
    • 5 Pages
    Decent Essays
  • Decent Essays

    Fuel Cells

    • 928 Words
    • 4 Pages

    (1) The diffusion flux created according to this linear concentration gradient in the steady-state balances accurately in the catalyst layer. (2) Here, j is the current density in the fuel cell and is the diffusion flux…

    • 928 Words
    • 4 Pages
    Decent Essays