Review heat transfer to Newtonian fluids in mechanically agitated vessels

Mohan, Pankaj; Emery, A. N.; Al‐Hassan, Tariq

doi:10.1016/0894-1777(92)90130-w

Cited by 43 publications

(34 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…[2] Mohan et al [3] reported that power s is within range 0.18 − 0.24 and it is dependent on the type of agitator and system geometry. Whitaker [4,5] published the correlation describing the heat transfer in a cross flow around a cylinder (of infinite length) with power s = 0.25.…”

Section: Introductionmentioning

confidence: 99%

Analysis of heat transfer in a vessel with helical pipe coil and multistage impeller

et al. 2014

View full text Add to dashboard Cite

Results of heat transfer coefficient measurements in an agitated vessel heated or cooled by the liquid media flowing in a helical pipe coil are presented in this paper. The multistage impeller made of two pitched six-blade impellers and adjustable clearance was used in a vessel with conical bottom. The transient method based on measuring the temperature dependency on time and solving the unsteady enthalpy balance was used to determine the heat transfer coefficients between the agitated liquid and the helical pipe coil. The results are summarized by the Nusselt number correlations, which describe the dependency on the impeller Reynolds number. The second part of this paper introduces a theoretical analysis of the flow in the liquid batch near the helical pipe coil. Based on the known pumping capacity of the multistage impeller, the characteristic velocity near the helical pipe coil can be evaluated. This characteristic velocity can be then used to determine the Nusselt number describing the heat transfer in a flow around a cylinder with the same cross-section profile as the helical pipe coil. A clear correlation between this Nusselt number and the integral Nusselt number is presented in this paper and introduces an alternative approach for prediction of heat transfer characteristics on the basis of hydrodynamic parameters describing an agitated system.

show abstract

Section: Introductionmentioning

confidence: 99%

Analysis of heat transfer in a vessel with helical pipe coil and multistage impeller

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The large bracket term represents the thermal effectiveness, previously defined in eq. (6). The grouping in the exponential terms of these equations is labelled the dimensionless number of heat transfer units, N T U , and is the ratio of the heat transfer capacity, U A, of the vessel to the heat capacity of the flow,Ṁ c p .…”

Section: Kays and London 1984mentioning

confidence: 99%

“…Residence time in the jacket is small When compared to the duration of heating or cooling 4 The process fluid is perfectly mixed High impeller speed used (large Reynolds number flow) 5 Jacket flow rate is fixed The thermoregulator has a fixed speed pump 6 Heat capacities are time invariant Valid when the heat capacities do not depend strongly on temperature and concentration of the reactants 7…”

Section: Introductionmentioning

confidence: 99%

Assessment of Overall Heat Transfer Coefficient Models to Predict the Performance of Laboratory-Scale Jacketed Batch Reactors

Johnson

Heggs

Mahmud

2016

Org. Process Res. Dev.

View full text Add to dashboard Cite

Heat transfer models for agitated, jacketed, laboratory-scale batch reactors are required to predict process temperature profiles with great accuracy for tasks associated with chemical process development such as batch crystallisation and chemical reaction kinetics modelling. The standard approach uses a reduced model which assumes the system can be adequately represented by a single overall heat transfer coefficient which is independent of time, however the performance of reduced models for predicting the evolution of process temperature is rarely discussed. Laboratory scale (0.5 and 5 l) experiments were conducted using a Huber thermoregulator to deliver a thermal fluid at constant flow to a heat transfer jacket. It is demonstrated that the relative specific heat contribution of the reactor and inserts represent an increasing obstacle for these transient models with decreasing scale. However, a series of experiments implied that thermal losses were the limiting factor in the performance of a single coefficient reduced model at laboratory-scale. A diabatic model is presented which accounts for both thermal losses and the thermal inertia of the reactor vessel and inserts by incorporating a second coefficient and a modified heat capacity term. The mean absolute error in predicted process temperature was thereby reduced by a factor of eight, from 2.4 to 0.3 K, over a 150 min experiment.

show abstract

“…Mohan et al [17] presented a review of the heat transfer in agitated vessels. This work focused on heat transfer in single-phase and two-phase (gas-liquid) agitated systems equipped with either jacket or heat transfer coils.…”

Section: Introductionmentioning

confidence: 99%

“…Many papers can be found about heat transfer in the whole vessel (Wichterle [16], Mohan et al [17], Akse et al [5], Karcz [7]) but only a few deal with local heat transfer coefficients at the bottom of the agitated vessel or at the vessel wall (Karcz and Cudak [18], Engeskaug et al [19], Mohan et al [17] and Akse et al [5]). …”

Section: Introductionmentioning

confidence: 99%

Application of the Temperature Oscillation Method in Heat Transfer Measurements at the Wall of an Agitated Vessel

et al. 2018

View full text Add to dashboard Cite

Abstract. The Temperature Oscillation Infra-Red Thermography (TOIRT) was used to measure convective heat transfer coefficients at the inner vertical wall of an agitated and baffled vessel. Two impellers were used: an axial six-blade impeller with pitched blades and the Rushton turbine. The TOIRT method represents an indirect method based on measuring the phase shift between the oscillating heat flux applied to one side of the heat transfer surface and the wall temperature response monitored by a contactless infra-red camera at the same side. On the basis of this phase shift, the TOIRT method can indirectly evaluate the heat transfer coefficient on the other side of the heat transfer surface. Two forms of experimental results are presented in this paper. The first one describes graphical dependencies of the local Nusselt number on the dimensionless distance from the vessel bottom for various Reynolds numbers. The second form describes the mean Nusselt number along the wall as a function of the Reynolds number.

show abstract

Review heat transfer to Newtonian fluids in mechanically agitated vessels

Cited by 43 publications

References 22 publications

Analysis of heat transfer in a vessel with helical pipe coil and multistage impeller

Analysis of heat transfer in a vessel with helical pipe coil and multistage impeller

Assessment of Overall Heat Transfer Coefficient Models to Predict the Performance of Laboratory-Scale Jacketed Batch Reactors

Application of the Temperature Oscillation Method in Heat Transfer Measurements at the Wall of an Agitated Vessel

Contact Info

Product

Resources

About