Heat Exchanger Simulation

Heat duty is the energy crossing per unit time, fixed by the streams’ mass flows and heat capacities and the achievable temperature approach. DyssolPro computes it directly from the two streams’ mass flows and heat capacities and your exchange efficiency, returning the duty and both outlet temperatures.

The standard move is to recover hot exhaust heat to preheat the incoming air or feed. In DyssolPro you connect the dryer or kiln exhaust to a heat exchanger against the cold feed, set the efficiency, and read off the recovered duty and the preheated-stream temperature.

Rapid fouling comes from deposition, scaling, or particle build-up on the surfaces — an operational/chemical effect the model doesn’t simulate. DyssolPro represents performance through the exchange efficiency, so a measured drop in effectiveness signals fouling; you study its process impact by lowering the efficiency.

Direct heating mixes a hot medium into the stream; indirect keeps them separate through a wall. DyssolPro’s heat exchanger is the indirect case (energy only, no mixing); a direct-contact arrangement would instead be modelled by mixing the streams, so the two are distinct units in the flowsheet.

Deposits add a resistance that lowers the real heat transfer, i.e. the effectiveness. DyssolPro doesn’t model the deposit mechanistically, but you capture its effect by reducing the exchange efficiency and study how the duty and outlet temperatures respond.

Steam (external heating) falls when more of the duty is met by recovered process heat. DyssolPro lets you add recovery exchangers and study how their efficiency and arrangement reduce the residual heating needed, trimming steam use.

Outlet temperature swings come from fluctuating inlet temperatures or flows on either side. In a dynamic flowsheet DyssolPro propagates those inlet variations through the energy balance to the outlet, so you can study how upstream upsets reach the exchanger outlet.

Mechanical sizing needs the required area from a heat-transfer coefficient — a separate calculation. DyssolPro works at the effectiveness level: for a target efficiency it gives the duty and outlet temperatures, defining the duty the area must then be sized to deliver.

Scaling is a fouling chemistry problem (water hardness, temperature, velocity) outside the model. DyssolPro covers the energy exchange; scaling’s effect is represented as a reduced efficiency, while its prevention is a materials/operation matter.

This is exactly the unit’s strength: it exchanges energy between two streams of any phase using their heat capacities and mass flows. In DyssolPro you connect the two streams, set the efficiency, and the energy balance gives the heat transferred and both outlet temperatures regardless of phase.

Network optimization (pinch analysis) maximizes internal heat recovery across many exchangers. DyssolPro lets you build the network of heat-exchanger units in the flowsheet, set their efficiencies, and study the overall recovery to find an energy-efficient arrangement.

A lower-than-expected outlet usually means the real effectiveness is below the design value — often fouling or a flow imbalance. DyssolPro lets you compare outlet temperatures at the assumed and a reduced efficiency, so you can infer the effectiveness the unit is actually achieving.

Viscosity lowers the real heat transfer coefficient and thus the effectiveness, and raises pressure drop. DyssolPro lumps the transfer into the efficiency rather than computing it from viscosity, so a more viscous slurry is represented by a lower efficiency; the coefficient/pressure-drop detail is a separate design step.

Fouling is reduced by higher velocities, smoother surfaces, and cleanable geometries (e.g. plate or spiral units) — equipment choices. DyssolPro models the resulting performance via efficiency, not the fouling mechanism, so it quantifies the process effect while the mitigation stays mechanical.

Degradation happens when a sensitive stream is taken above its temperature limit. DyssolPro computes the outlet temperatures, so you can choose stream pairings and efficiency that deliver the required heating while keeping the sensitive stream below its degradation threshold.

The overall coefficient U comes from the film coefficients and wall resistance via correlations — a geometry-level calculation. DyssolPro doesn’t compute U; it uses a lumped exchange efficiency instead, so U is a separate design step, though the duty DyssolPro returns is what a U-based sizing must achieve.

Dryer exhaust carries recoverable sensible heat. In DyssolPro you connect the exhaust stream to a heat exchanger against a cold inlet (e.g. fresh drying air), set the efficiency, and quantify the recovered heat and the preheat achieved.

Plate units give higher effectiveness and easy cleaning; shell-and-tube handle higher pressures and fouling. DyssolPro models the energy exchange through the efficiency regardless of type, so you set the efficiency to match the candidate’s performance and compare the process outcomes.

Within a dynamic flowsheet DyssolPro propagates changing inlet temperatures and flows through the exchanger’s energy balance to the outlets. It represents the energy exchange rather than the wall’s thermal inertia, so fast transients dominated by thermal lag are an approximation — the steady energy response is well captured.

Particle-laden gas raises fouling and erosion concerns that drive the equipment choice (e.g. spiral or tubular). DyssolPro models the energy exchange treating the gas–solids stream’s heat capacity and mass flow, giving the duty and outlet temperatures; the fouling/erosion handling is an equipment-design matter.