Scraped Surface Heat Exchangers Overview

They used a saturated NaCl solution as the disturbance and measured response with a conductivity bridge at periodic intervals.

They suggested that the fastest moving particle must be used for process calculations.

They performed experimental RTD work on mixtures of water and calcium alginate beads, analyzing physical and fluid properties.

<p>They found that increased particle diameter, mutator speed, and flow rate narrowed the RTD, while carrier fluid viscosity had no effect.</p> Signup and view all the answers

<p>They used videotaping to detect tracer particles flowing through the system.</p> Signup and view all the answers

<p>They studied the influence of processing conditions on particle damage as a function of residence time distribution.</p> Signup and view all the answers

<p>They proposed introducing particles as a pulse for evaluating the RTD of the scraped surface heat exchanger.</p> Signup and view all the answers

<p>Lee and Singh were the researchers who developed these mathematical models.</p> Signup and view all the answers

<p>Radial blades provide high pressure with medium flow and are efficient in handling dust-laden, moist air or gases.</p> Signup and view all the answers

<p>Air volume required (CFM) and system resistance are two key selection criteria for fans and blowers.</p> Signup and view all the answers

<p>Forward curved blades are used in low-pressure applications, such as HVAC systems and packaged units for clean and dust-laden air.</p> Signup and view all the answers

<p>Factors include air density, type of service, environment type, and temperature of operation.</p> Signup and view all the answers

<p>Radial blades have lower efficiency compared to forward curved blades, which tend to have higher efficiency in low-pressure applications.</p> Signup and view all the answers

<p>The drive type, whether direct or belt, impacts the installation, maintenance, and operational cost of the fan system.</p> Signup and view all the answers

<p>Axial fans typically have lower pressure capabilities and are known for higher flow rates, while centrifugal fans generate higher pressure with moderate flow.</p> Signup and view all the answers

<p>It's essential to consider the noise criteria, as they can affect the environment in which the fan operates.</p> Signup and view all the answers

<p>Thin film SSHEs can handle viscosity variation, heat sensitivity, and foaming in process fluids.</p> Signup and view all the answers

<p>Thin film SSHEs typically use a double pipe construction, with the scraping mechanism located in the inner pipe where the process fluid flows.</p> Signup and view all the answers

<p>Heat transfer in liquid full vertical SSHEs is facilitated by the rotation of blades, which scrape the product off the heat transfer tube surface.</p> Signup and view all the answers

<p>Spring loaded scraper blades in thin film SSHEs help continuously remove the processed fluid from the inner surface to enhance heat transfer.</p> Signup and view all the answers

<p>In liquid full vertical SSHEs, gravity causes the product to fall down along the inner side of the heat transfer tube.</p> Signup and view all the answers

<p>Centrifugal force in liquid full SSHEs throws the product back onto the heat transfer tube's surface, promoting better heat transfer.</p> Signup and view all the answers

<p>Thin film SSHEs are designed to manage complex fluid behaviors, while liquid full SSHEs rely on gravity and blade rotation for heat transfer.</p> Signup and view all the answers

<p>Thin film SSHEs can address issues such as viscosity variation, heat sensitivity, and foaming during food processing.</p> Signup and view all the answers

<p>They provide high efficiency and power reduction as flow increases beyond the point of highest efficiency.</p> Signup and view all the answers

<p>They are used in HVAC systems, drying processes, and exhaust systems.</p> Signup and view all the answers

<p>A mathematical modeling approach is used to predict temperature and shear conditions inside the heat exchanger.</p> Signup and view all the answers

<p>The influence of rotational speed on the heat transfer coefficient is not directly proportional.</p> Signup and view all the answers

<p>Propeller fans operate at low pressure and high flow rate, achieving peak efficiency at zero static pressure.</p> Signup and view all the answers

<p>SSHEs are used for crystallization of margarine, tempering of chocolate, and freezing of ice cream and sorbet.</p> Signup and view all the answers

<p>They use guide vanes to direct airflow, which results in higher efficiency in high-pressure applications.</p> Signup and view all the answers

<p>Crystal size distribution and apparent viscosity are determined by the operating conditions, which directly affect product quality.</p> Signup and view all the answers

<p>The pressure rise across a fan is usually a few millimeters of water gauge, while a blower can exceed 1000 mm of water gauge.</p> Signup and view all the answers

<p>Centrifugal force generates static pressure while causing the deflection of airflow by the blades.</p> Signup and view all the answers

<p>SSHEs can handle viscous products, particles, and prevent fouling, making them versatile for various food processing needs.</p> Signup and view all the answers

<p>Rotating scraper blades remove deposits on the heat exchanger surface, maintaining heat transfer rates.</p> Signup and view all the answers

<p>Airfoil type fans provide higher efficiency and are specifically designed for clean air applications.</p> Signup and view all the answers

<p>Forward curved blades create strong air deflections that critically influence both the flow pattern and performance.</p> Signup and view all the answers

<p>They are critical in formulating the model for heat transfer in the scraped-surface heat exchanger.</p> Signup and view all the answers

<p>Direct measurement is challenging due to the complex and dynamic environment within the freezer barrel.</p> Signup and view all the answers

<p>The critical factors include residence time distribution of particulate matter, overall heat transfer coefficients, and potential damage to the particulates.</p> Signup and view all the answers

<p>Higher levels of denaturation in whey proteins produced softer cheeses with a lower elastic modulus, while native whey proteins resulted in a denser network structure.</p> Signup and view all the answers

<p>Cheeses with high levels of native whey proteins did not melt, whereas those with high levels of denatured whey proteins melted upon heating.</p> Signup and view all the answers

<p>Denatured whey proteins form large aggregates that disrupt the cheese structure, while native whey proteins create a more cohesive matrix.</p> Signup and view all the answers

<p>Some products include basundi, kulfi mix, kheer, khoa, peda, thabdi, burfi, gajar halwa, and dhudhi halwa.</p> Signup and view all the answers

<p>SSHE enhances the chilling process and helps in maintaining the quality and shelf life of the products.</p> Signup and view all the answers

<p>Maintaining rheological qualities ensures improved texture, consistency, and overall consumer acceptance while optimizing processing costs.</p> Signup and view all the answers

<p>Scrapers ensure constant agitation and a thin film of product, enhancing heat transfer rates and preventing burn-on in the processing equipment.</p> Signup and view all the answers