Optimal design of plate-and-frame heat exchangers for efficient heat recovery in process industries

The developments in design theory of plate heat exchangers, as a tool to increase heat recovery and efficiency of energy usage, are discussed. The optimal design of a multi-pass plate-and-frame heat exchanger with mixed grouping of plates is considered. The optimizing variables include the number of passes for both streams, the numbers of plates with different corrugation geometries in each pass, and the plate type and size. To estimate the value of the objective function in a space of optimizing variables the mathematical model of a plate heat exchanger is developed. To account for the multi-pass arrangement, the heat exchanger is presented as a number of plate packs with co- and counter-current directions of streams, for which the system of algebraic equations in matrix form is readily obtainable. To account for the thermal and hydraulic performance of channels between plates with different geometrical forms of corrugations, the exponents and coefficients in formulas to calculate the heat transfer coefficients and friction factors are used as model parameters. These parameters are reported for a number of industrially manufactured plates. The described approach is implemented in software for plate heat exchangers calculation

Computer Aided Design of Plate Heat Exchangers

The computer aided design of plate heat exchanger with mixed grouping of plates is considered. It is formulated as the mathematical problem of finding the minimal value for implicit nonlinear discrete/continues objective function with inequality constraints. The optimizing variables include the number of passes for both streams, the numbers of plates with different corrugation geometries in each pass, the plate type and its size. To estimate the value of objective function in a space of optimizing variables the mathematical model of plate heat exchanger is developed. To account for thermal and hydraulic performance of channels between plates with different geometrical forms of corrugations, the exponents and coefficients in formulas for heat transfer coefficients and friction factors calculation are used as model parameters. The procedure and software for numerical experiment to identify model parameters by comparing the calculation results with those obtained with free available in web computer programs of plate manufacturers is developed. The sets of such parameters are obtained for a number of industrially manufactured plates. The described approach is implemented as software for plate heat exchangers calculation

Shell-and-Plate Heat Exchangers for Efficient Heat Recovery under the Industrial Application

The developments in design theory of Shell-and-Plate Heat Exchangers (SPHE), aiming to enhance the heat recovery and efficiency of energy usage, are discussed. The thermal and hydraulic performance of the unit is estimated using two approaches: by proper selection of plate corrugation pattern and by the adjustment of plates with different height of corrugation in one unit. The optimization problem targeting the minimal heat transfer area under the requirements of proper operating conditions is observed. The optimizing variables include the number of plates with different corrugation geometries in one pass. To estimate the value of the objective function in a space of optimizing variables the mathematical model of SPHE is developed. The possibilities of their application as heat exchangers in preheat train of crude oil distillation unit of the oil refinery are analysed basing on obtained design parameters with the effect of flow movement arrangement in the unit and its influence on shear stress and fouling formation. The comparison with another Compabloc type welded PHE is discussed

Shell-and-Plate Heat Exchangers for Efficient Heat Recovery under the Industrial Application

The developments in design theory of Shell-and-Plate Heat Exchangers (SPHE), aiming to enhance the heat recovery and efficiency of energy usage, are discussed. The thermal and hydraulic performance of the unit is estimated using two approaches: by proper selection of plate corrugation pattern and by the adjustment of plates with different height of corrugation in one unit. The optimization problem targeting the minimal heat transfer area under the requirements of proper operating conditions is observed. The optimizing variables include the number of plates with different corrugation geometries in one pass. To estimate the value of the objective function in a space of optimizing variables the mathematical model of SPHE is developed. The possibilities of their application as heat exchangers in preheat train of crude oil distillation unit of the oil refinery are analysed basing on obtained design parameters with the effect of flow movement arrangement in the unit and its influence on shear stress and fouling formation. The comparison with another Compabloc type welded PHE is discussed

The New Corrugation Pattern for Low Pressure Plate Condensers

Low pressure and especially vacuum vapours condensation processes are widely used in different industries such as power generation, chemical, biochemical, pharmaceutical, food etc. Plate Heat Exchangers (PHEs) are one of the modern efficient types of heat transfer equipment, but their usage as condensers for low pressure vapour is limited mostly because of relatively high pressure drop of condensing media. To overcome this obstacle the new principle of plate corrugation for low pressure plate-and-frame condensers is proposed. The basic trends on developments of corrugated patterns for low pressure plate condensers were investigated. The principle of channels with variable geometry was selected for new corrugated pattern development. The proposed plate for condenser has the heat transfer area that consists of several corrugated sections along its length. Shape and dimensions of ridges and valleys of corrugations are variable. The corrugations are inclined to plate vertical axis so the ridges of two adjacent plate corrugations are in contact. The channel formed by such plates has the variable cross-section area. The experimental study of heat transfer and pressure drop for channels of such pattern was carried out. The dependencies for film heat transfer and pressure drop were obtained for each channel part formed with adjacent sections of the plates. The obtained results were compared with those for plates which are conventionally used. The advantages of proposed corrugation are discussed. The calculation methods based on obtained results were developed for single-phase flows heat exchange and for condensation of pure vacuum vapours. The recommendations on plate surface synthesis are presented

The influence of plate corrugations geometry on plate heat exchanger performance in specified process conditions

The mathematical model of plate heat exchanger (PHE) is developed using decomposition of the plate on its main corrugated field, which cause major effect on heat transfer, and distribution zone, which influences mostly the hydraulic performance. Model is validated on experimental data for some commercial plates. It is shown, that for specified pressure drop, temperature program and heat load the geometrical parameters of plate and its corrugations, which are enable to make PHE with minimal heat transfer area, can be found. The developed mathematical model can be used for designing of plates with geometry, which is in the best way satisfying process conditions of the certain specific range. The case study for conditions of PHE application in District Heating systems is presented

Heat Transfer and Pressure Drop in Cross-Flow Welded Plate Heat Exchanger for Ammonia Synthesis Column

Plate Heat Exchanger (PHE) is one of the modern types of compact heat transfer equipment, which can significantly enhance the heat recuperation and improve efficiency of energy usage in many industrial applications. The construction of welded PHE (WPHE) can significantly widen the range of its application on temperature and pressure. The results of experimental study of heat transfer and pressure drop in a model of WPHE specially designed for work in ammonia synthesis columns are presented. The model consists of the round plates with special form of corrugations. The plates are welded together forming a pack with channels for two heat exchanging streams. The streams are in a cross flow that correspond to one pass of the multipass WPHE with overall counter-current flow. It is shown that for calculation of heat transfer effectiveness can be used the cross flow model where fluid in one channel is mixed, but in another unmixed. The Equations for calculation of film heat transfer coefficients and pressure drop are presented, which can be used in earlier developed method of WPHE design. The validity of the Equations and developed method of WPHE design is confirmed by the data of tests with WPHE installed in ammonia synthesis column at temperature up to 520 °C and pressure 32 MPa

Ammonia Refrigeration Cycle Integration in Buildings Heating System

This work investigates the possibility of ammonia low potential heat utilisation with use of Process Integration methodology. The two operation modes are considered. The first one is the use of ammonia gas super-heating and partly ammonia condensation. The low condensation temperature of ammonia is limiting the low potential heat usage. The second option is introduction of ammonia additional compression to increase the temperature of ammonia condensation. The low potential heat consumers are the hot water supply system, air pre-heating system and air heating for the fans

Characterization of one-dimensional quantum channels in InAs/AlSb

We report the magnetoresistance characteristics of one-dimensional electrons confined in a single InAs quantum well sandwiched between AlSb barriers. As a result of a novel nanofabrication scheme that utilizes a 3nm-shallow wet chemical etching to define the electrostatic lateral confinement, the system is found to possess three important properties: specular boundary scattering, a strong lateral confinement potential, and a conducting channel width that is approximately the lithography width. Ballistic transport phenomena, including the quenching of the Hall resistance, the last Hall plateau, and a strong negative bend resistance, are observed at 4K in cross junctions with sharp corners. In a ring geometry, we have observed Aharonov-Bohm interference that exhibits characteristics different from those of the GaAs counterpart due to the ballistic nature of electron transport and the narrowness of the conducting channel width.Comment: pdf-file, 8 figures, to be published in Phys. Rev.