WinGEMS modelling and pinch analysis of a paper machine for utility reduction

A multi-ply paper machine process model was developed using WinGEMS and the stream data produced was used to conduct a pinch analysis. The product stream was excluded from the analysis and the composite curves display the enthalpy contained only in the inputs and outputs to the various sections of the paper machine. The pinch point for the overall paper machine was 55.9 C while the minimum hot utility target was 170 MW. Occurrences of cross pinch heat transfer were identified and discussed. Heat recovery options for heating of the fresh water showers, using waste heat streams were investigated. Steam savings of over 14 MW could be achieved by recovering heat from two waste streams that currently go directly to drain with no heat recovery taking place. The use of pinch analysis for utilities targeting under non-continuous conditions was examined. Finally, the feasibility of integrating non-conventional technologies, such as heat storage, is discussed

Study of Adhesive Strength in Polymer Plate Heat and Mass Exchanger

Open Cycle Liquid Desiccant Air Conditioner system is promising solution for air conditioning in hot and humid climates like a tropical region South East Asia. The system used cross flow type plate heat exchanger made by thin sheets of polymer for both dehumidification and cooling. However leakage between the polymer sheets is due to adhesive failure of joint between plastic sheet results in a decreasing of regenerator performance. The objectives of this project are to fabricate and simulate model of plate heat and mass exchanger and to study the adhesive strength used for heat and mass exchanger. The methodology for this project is started with the design of prototype plate heat and mass exchanger and material selection such as cyanoacrylate adhesive, silicon sealant and EVA Hot Melt Adhesive based on their properties and also polypropylene material as corrugated sheet and solid sheet material. Prior to adhesive test, heat treatment and surface roughening are prepared as surface preparation together with step to apply the adhesive to sample test. In order to test the maximum strength of the adhesive, the Single Lap Joint Shear Test is chosen for the adhesive test. After satisfying with the performance of adhesive, the fabrication of the heat and mass exchanger is started. Hydro testing of the model is conducted to test the leaking problem and also HMX working principle. 2D Design of Regenerator is designed to illustrate the model of plate heat and mass exchanger. Material selection for each component of regenerator is summarized by Bill of Material of Plate Heat and Mass Exchanger. From the single lap joint shear test, PP sample with treated surface bonded with cyanoacryalate adhesive achieved highest shear strength, 3.61MPa compared to untreated surface PP sample and other adhesive sample test. Besides, the result of hydro testing are also discussing about leaking problem of adhesive and also working principle of model. Most of leakage problem occurred due to improper fabrication technique and improper sealant used. Sealant of plastic joint is replaced from silicon sealant to EVA Hot Melt Adhesive. This adhesive able to fill the gap between the joint and resist the water from leaked. As a result, the leakage problem is minimized by using EVA Hot Melt Adhesive

Bond Graph model of a vertical U-tube steam condenser coupled with a heat exchanger.

International audienceA simulation model for a vertical U-tube steam condenser in which the condensate is stored at the bottom well is developed in this paper. The U-tubes carrying the coolant are partially submerged in the stored condensate and thus the bottom well acts as a heat exchanger. The storage of hydraulic and thermal energies is represented using a coupled pseudo-bond graph model. Advection effects are modelled by considering reticulated segments of the tubes carrying coolant, over which condensation takes place. The developed model is of intermediate complexity and it is intended for use in observer based real time process supervision, which works by comparing the process behaviour to the reference model outputs. The simulation results obtained from the bond graph model are validated with experimental data from a laboratory set-up

A review of metal foam and metal matrix composites for heat exchangers and heat Sinks

Recent advances in manufacturing methods open the possibility for broader use of metal foams and metal matrix composites (MMCs) for heat exchangers, and these materials can have tailored material properties. Metal foams in particular combine a number of interesting properties from a heat exchanger's point of view. In this paper, the material properties of metal foams and MMCs are surveyed, and the current state of the art is reviewed for heat exchanger applications. Four different applications are considered: liquid-liquid, liquid-gas, and gas-gas heat exchangers and heat sinks. Manufacturing and implementation issues are identified and discussed, and it is concluded that these materials hold promise both for heat exchangers and heat sinks, but that some key issues still need to be solved before broad-scale application is possible

Repurposing of disused shale gas wells for subsurface heat storage: preliminary analysis concerning UK issues

Development of many wells is envisaged in the UK in coming decades to exploit the abundant shale gas resource as fuel and petrochemical feedstock. Forward planning is therefore warranted regarding reuse of the resulting subsurface infrastructure after gas production has ceased. It is shown that this infrastructure might be repurposed for borehole thermal energy storage (BTES). Preliminary calculations, assuming an idealized cycle of summer heat storage and winter heat extraction, indeed demonstrate annual storage of c. 6 TJ or c. 2 GWh of energy per BTES well. Summed over the anticipated well inventory, a significant proportion of the UK's future heat demand might thus be supplied. This form of BTES technology has particular relevance to the UK, where the shale resource is located in relatively densely populated areas; it is especially significant for Scotland, where the resource coincides with a particularly high proportion of the population and heat demand

Simulation of multi-deck medium temperature display cabinets with the integration of CFD and cooling coil models

This is the post-print version of the final paper published in Applied Energy. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2010 Elsevier B.V.In this paper, the model for the multi-deck medium temperature display cabinets is developed with the integration of CFD and cooling coil sub-models. The distributed method is used to develop the cooling coil model with the airside inputs from the outputs of the CFD model. Inversely, the airside outputs from the cooling coil model are used to update the boundary conditions of the CFD model. To validate this cabinet model, a multi-deck medium temperature display cabinet refrigerated with a secondary refrigerant cooling coil was selected as a prototype and mounted in an air conditioned chamber. Extensive tests were conducted at constant space air temperature and varied relative humilities. The cabinet model has been validated by comparing with the test results for the parameters of air at different locations of the flow path, and temperatures of refrigerant and food product, etc. The validated model is therefore used to explore and analyse the cabinet performance and control strategies at various operating and design conditions.DEFR

A discretization method for the characterization of a plate heat exchanger working as evaporator during transient conditions

In this work, a method for the characterization of a plate heat exchanger working as evaporator is presented. It is based on a one-dimensional discretization of the exchanger, which solves the heat transfer balance equations by means of an iterative methodology based on a heat transfer area converging method. The inputs of the method are the flow rates of the fluids, the inlet enthalpy of the refrigerant, the superheating, and the inlet temperature and pressure of the secondary fluid. Once the inlet pressure of the refrigerant is assumed, pressure drop is calculated in each cell and then enthalpy. The consideration of the proper heat transfer coefficient (HTC) correlations allows the calculation of the heat transfer area, which is after compared to the actual one. The method has been validated by means of a database of 366 experimental data obtained for eight plate heat exchangers working as evaporators by using six different refrigerants, namely R134a, R1234yf, R513A, R744, R290, and R507A. As the method requires suitable correlations for the calculation of the HTC and pressure drop, several correlations for the HTC and Δp found in the literature are studied and the results obtained by using them are presented in terms of the maximum absolute relative deviation (MARD). The results corresponding to the correlation which yields the best results are graphically represented. Finally, the method is used to predict the evaporator performance operating in transient conditions. The results obtained show an excellent agreement with the experimental results collected during the transient operation of a transcritical CO2 water heater coupled to a storage tank.The work in this paper has been financed by the Spanish Ministry of Science and Innovation under Project TED2021-131173B–I00 and the NextGenerationEU recovery plan

experimental and numerical study of a parabolic trough linear cpvt system

Abstract The electric and thermal performance of a parabolic trough linear concentrating photovoltaic-thermal (CPVT) system operating in Padova (northern Italy) is experimentally investigated. The system moves about two axes and exhibits a geometrical concentration ratio around 130. The receiving module placed on the focus line displays a secondary optics made of two flat mirrors to gather some reflected radiation and to contribute to the concentrated flux on two lines of triple junction photovoltaic cells soldered on a ceramic substrate. The substrate is in thermal contact with a aluminium heat exchanger with water flow channels to cool the PV cells. During the test runs, the inlet water temperature ranges from 20 °C to 80 °C and the heat yield is obtained from mass flow rate and temperature measurements while a rheostat and a power analyzer are connected to the electric terminals of the module to assess the electrical production. The direct normal irradiation (DNI) is measured by a pyrherliometer mounted on a solar tracker. Experimental results are used to assess a numerical model of the solar receiver and the whole concentrator

HITRAN® WIRE MATRIX INSERTS IN FOULING APPLICATIONS

Fouling characteristics are dictated largely by the properties of the thermal and hydrodynamic boundary layers. As a result, fouling mitigation strategies must take into account the conditions in this region. hiTRAN® wire matrix tube inserts are a useful tool in altering the conditions near the tube wall, especially in the laminar and transition flow regions. This review paper considers Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) measurements, which were employed in order to show the hydrodynamic differences between plain tubes and those containing inserts. Measurements indicate that the wall shear rate in tubes containing hiTRAN® inserts operating in the laminar flow regime is similar to that for plain bore tubes operating in the turbulent flow regime. Moreover, the increased tube side heat transfer coefficient which results from the reduction of the thermal boundary layer allows operation with smaller EMTDs. This enables the designer to reduce the tube wall temperature to a level below the fouling threshold temperature, e.g. to combat crude oil fouling. The results from the laser analyses into the hydrodynamic boundary layer are backed up by recent research data investigating the effect of hiTRAN® inserts on sedimentation and particulate fouling. The thickness of the fouling layer was measured by applying a combination of photographic and laser measurement techniques. The results are compared to plain tube data and are reported as a function of both flow rate and hiTRAN® insert packing density. The impact of altering the hydrodynamic and thermal conditions near to the wall is subsequently demonstrated for different fouling mechanisms. Studies of the impact of hiTRAN® inserts on biological and chemical reaction fouling in crude oil processing are also reviewed. A better understanding of the threshold shear rates and wall temperatures for different fouling mechanisms is required for any study into the impact of fouling. Combining this knowledge with the principles outlined in this paper clearly emphasises the benefit of using hiTRAN® wire matrix inserts as a powerful tool to mitigate fouling