This food product is produced in the form of small spheres or pellets by freezing it in the water freezer. Blast freezer air freezers operate at a temperature of -35 degrees Celsius The initial product temperature is 25 degrees Celsius.The pellets have a diameter of 0.5 cm and a density of 980 kg / m³ temperature initial freezing is -2.5 degrees Celsius latent heat of product manufacture is 280 kj / kg the thermal conductivity of frozen products is 1.9 W / (m degrees Celsius). Convection heat transfer coefficient is 50 W / (m² degrees Celsius) calculated freezing time. tf =

This food product is produced in the form of small spheres or pellets by freezing it in the water freezer. Blast freezer air freezers operate at a temperature of -35 degrees Celsius The initial product temperature is 25 degrees Celsius.The pellets have a diameter of 0.5 cm and a density of 980 kg / m³ temperature initial freezing is -2.5 degrees Celsius latent heat of product manufacture is 280 kj / kg the thermal conductivity of frozen products is 1.9 W / (m degrees Celsius). Convection heat transfer coefficient is 50 W / (m² degrees Celsius) calculated freezing time. tf =

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter6: Forced Convection Over Exterior Surfaces

Section: Chapter Questions

Problem 6.26P

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In a drying process, the moisture content of 35 kg of food will be reduced from 82% to 6%. The air used for drying enters the dryer at 80 ° C and exits at 70 ° C. To heat the air, 130 kg of saturated steam at 105 ° C is used. Food enters the dryer at 25 ° C and exits at 60 ° C. According to the ambient air temperature is 20 ° C; Calculate the drying efficiency based on evaporation latent heat and sensible heat. (Specific heat of food = 3.30 kJ / kg ° C)
NUMBER 4 A food product wants to be produced in a small round shape (pellet) by freezing it in a water blast freezer freezer. Air freezer operates at -30 ° C. The initial product temperature is 25 ° C. The pellet has a diameter of 0.5 cm, and a density of 980 kg / m³. The initial freezing temperature is -2.5 ° C. The latent heat of freezing of the product is 280 kJ / kg. The thermal conductivity of the frozen product is 1.9 W / (m ° C). The convective heat transfer coefficient is 50 W / (m² K). Calculate the freeze time. t f = hour.
2-D: A fin may be manufactured as an integral part of a surface by using a casting or extrusion process, or it may be separately brazed or adhered to the surface. From thermal considerations, which option is preferred? 2-E: What is the difference between steady-state and transient heat transfer processes? Give an example for each of them. 2-F: What is the physical interpretation of the Biot number? 2-G: For flow over a flat plate, sketch variation of local convective heat transfer coefficient, h(x), versus the distance along the plate x for laminar, transition, and turbulent flow regimes.
Number 4 A food product wants to be produced in a small round shape (pellet) by freezing it in a water blast freezer freezer. Air freezer operates at a temperature of -35 ° C. The initial product temperature is 25 ° C. The pellet has a diameter of 1.2 cm, and a density of 980 kg / m³. The initial freezing temperature is -2.5 ° C. The latent heat of freezing of the product is 280 kJ / kg. The thermal conductivity of the frozen product is 1.9 W / (m ° C). The convective heat transfer coefficient is 50 W / (m² K). Calculate the freeze time. identify : a. tf = Answer in hour
Chapter Va - 31 BOOK: ENGINEERING THERMOFLUIDS, M. MASSOUD
a cylindrical can of bean puree, has a diameter of 70 mm and height of 126 mm, and is initially at a uniform temperature of 25 ° C. The cans are stacked vertically inside a retort into which steam is introduced at 120 ° C. Calculate the temperature in the center of the can after a heating time of 0.55 h at 120 ° C. Now suppose the can is in the center of a vertical stack, insulated at its two ends by the presence of the remaining cans. (The heat capacity of the metal wall of the can can be neglected.) The heat transfer coefficient of steam is estimated to be 4640 W / m2 ° K. The physical properties of the bean are k = 0.750 W / m ° K and the thermal diffusivity = 2.007 x 10-7 m2 / s.a) Calculate the temperature in the center of the product.
Water has many unique molecular properties that make it extremely important. One application that takes advantage of these properties is a so-called evaporative cooler (or swamp cooler, https://en.wikipedia.org/wiki/ Evaporative_cooler), which is a device that cools air through the evaporation of water. Liquid water is changed into water vapor, whereby the energy used to evaporate the water (i.e. latent heat of vaporization) is consumed from the internal energy (i.e. temperature) of the air brought in from outside. The result is a lowering of the outside air temperature as it is brought inside. The process tends to also increase the humidity (vapor content) of the air. Hence it is an attractive option in some semi-arid regions where outside air is very hot and dry. a) What is the latent heat of vaporization for water? Is this value generally large or small compared to other substances? What are some of the implications of this? b) Suppose you have an evaporative cooler that has an…
PROBLEM: IIC-21 BOOK: ENGINEERING THERMOFLUIDS, M. MASSOUD
PROBLEM: IIC - 12 BOOK: ENGINEERING THERMOFLUIDS, M. MASSOUD
A moist cement omnes diameter 10 ohm circular cross-section will be dried using air in a tray and, for example, the variation of moisture content over time will be examined. The heat transfer coefficient was calculated as 0.68 cal/min.cm³.C in the fixed still drying arab. Dry and wet chamber temperatures of the air used for drying are 35 and 20°C, respectively. For example, calculate the mass transfer coefficient during the 10-minute constant speed drying interval. (Note: the humidity of the air (Ha) should be calculated with the humidity diagram.) Data Evaporation enthalpy of water: 2454.2 kj/kg at 20°C 2418.6 k/kg at 35C Vapor pressure of water: 17.54 mm Hg at 20°C. 35C is 42.18 mm Hg.
for COVID vaccine. The volume of the storage container will be 1 m³. You are debating on three shapes: (a) a rectangular shaped box with 20-cm thickness, 1-m 56.42 cm diameter, and width, and 5-m length; (b) a cylindrical storage with 4-m length and (a) a sphere. AS part of your design decision, find out the convective heat transfer rate from each of these containers. Assume the surface temperature to be uniform at –-10°C, and the ambient air is flowing at 20°C. The velocity of the air is 0.8 m/s. The direction of flow is over the 1-mx5-m sides of the box along the length (5-m) and across the cylinder and the sphere. Ignore the heat transfer from the end areas (i.e., the thickness of the rectangular box and the ends of the cylinder).
A food product wants to be produced in a small round shape (pellet) by freezing it in a water blast freezer freezer. Air freezer operates at a temperature of -35 ° C. The initial product temperature is 25 ° C. The pellet has a diameter of 1 cm, and a density of 980 kg / m³. The initial freezing temperature is -2.5 ° C. The latent heat of freezing of the product is 280 kJ / kg. The thermal conductivity of the frozen product is 1.9 W / (m ° C). The convective heat transfer coefficient is 50 W / (m² K). Calculate the freeze time. t f = hour