Fruit juices at 30 ° C containing 5% total solids were concentrated via a single effect evaporator. The evaporator is operated in a vacuum at an evaporation temperature of 80 ° C, and 90% quality steam is supplied at 169.06 kPa. The desired concentration of the final product is 40% total solids. The rate of concentrated product leaving the evaporator is 2000 kg / hour. The specific heat of fruit juice is 4.05 kJ / (kg ° C), and the concentrated product is 3,175 kJ / (kg ° C). Count a. The required steam rate is = kg / hour. b. Steam economy when the condensate temperature is released at 90 ° C. = (kg of water evaporates

A single effect evaporator is used to concentrate 10000 kg / hr of tomato juice from 5% total solids to 30% total solids. The juice enters the evaporator at 15 °C. The evaporator is operated on Steam (85% quality) at 143.27 kPa. The vacuum in the evaporator allows the juice to boil at 80 °C. The specific heat of the dilute material is 4.1 kJ / (kg ° C) and the concentrate product is 3.1 kJ / (kg °C). Count: a. Steam demand rate = Answer kg / hour. b. Steam economy when condensate temperature is released at 75 °C. = Answer (kg of water evaporated / kg of steam)

A rectangular block of material 4 (k-24 W/m °C), 0.1 m thick, is sandwiched between two walls of metals B (k, 230 W/m °C) and C (ke 200 W/m °C) of thicknesses 0.12 m and 0.15 m, respectively. The outer surface temperature of wall B is 100°C and that of wall C is 150°C. Heat generation occurs in A at a uniform volumetric rate of 2.5 × 10³ W/m². Develop equations for steady state temperature distributions in the three layers and the maximum temperature in the assembly. Also, calculate the percentage of total heat conducted out through the wall B. Assume one-dimensional heat flow.

A spherical container is used to store reacting chemicals, which results in a uniform heat flux (qi”) applied to the inner surface of the container. The initial temperature of the inner wall of the container, Ti, is 500K. The container has an inner radius of 0.4 m and an outer radius of 0.5 m, the density of the container’s walls are 8055 kg/m3, and its heat capacity is 535 J/(kg-K). The container is then suddenly submerged in a liquid bath with a temperature T∞=300K. The  convective heat transfer coefficient for the bath: h= 450 W/(m2 K).(a) Assume that there is a negligible thermal gradient in the wall of the container (dT/dr is negligible) and that the heat flux qi” is constant, write an equation that expresses how the temperature of the wall of the container changes with time (dT/dt) and evaluate the initial rate of change of wall temperature (dT/dt ) when qi”=106 W/m2.(b) What is the steady state temperature of the wall?

A liquid metal Gows at a rate of 5 kg/sec through a 5 cm diameter stainless steel tube. It enters at 425°C and is heated to 450°C as it passes through the tube. If a constant heat flux is maintained along the tube and the tube wall is at a temperature 20°C higher than the liquid metal bulk temperature, calculate the area required to effect the heat transfer. At constant heat flux, Nu = 4.82 +0.0185PE0.827 relation holds good. Properties of the compound: µ = 1.34 x 10-3 kg/m.sec; Cp W/m.K; Pr = 0.013. 0.149 kJ/kg.K; k = 15.6 %3D

8.4-10. Surface Area and Steam Consumption of an Evaporator. A single-effect evapo- rator is concentrating a feed solution of organic colloids from 5 to 50 wt %. The solution has a negligible boiling-point elevation. The heat capacity of the feed is c, = 4.06 kJ/kg K (0.97 btu/lbF) and the feed enters at 15.6°C (60°F). Satu- rated steam at 101.32 kPa is available for heating, and the pressure in the vapor space of the evaporator is 15.3 kPa. A total of 4536 kg/h (10000 lb/h) of water is to be evaporated. The overall heat-transfer coefficient is 1988 W/m² · K (350 btu/h ft2F). What is the required surface area in m? and the steam consump- tion?

Fruit juice at 25 ° Celsius contains 5% total solids concentrated via single effect evaporator. Evaporator operated vacuum at 80 ° Celsius evaporation temperature and 85% quality steam supplied at 169.06 kPa. The desired concentration of the final product is 40%. The total solids rate of the concentrated product leaving the evaporator is 2500 kg / hr. the specific heat of fruit juice is 4.05 KJ / (kg degrees Celsius) and concentrated products 3.175 KJ / (per kg degrees Celsius) Count a. The required vapor rate is = b. steam economy if the condensate temperature is released at 90 ° Celsius =

Fruit juices at 25 °C containing 5% total solids were concentrated via a single effect evaporator. The evaporator is operated in a vacuum at an evaporation temperature of 80 °C, and 85% quality steam is supplied at 169.06 kPa. The desired concentration of the final product is 40% total solids. The rate of concentrated product leaving the evaporator is 3000 kg / hour. The specific heat of fruit juice is 4.05 kJ / (kg °C), and the concentrated product 3.175 kJ / (kg °C). Count : a. The required steam rate is = Answer kg / hour. b. Steam economy if the condensate temperature cannot be released at 90 °C. = Answer (kg evaporated air / kg vapor)

only b

A single effect evaporator was used to concentrate 8000 kg / hr of tomato juice from 5% total solids to 30% total solids. The juice enters the evaporator at 15 ° Celsius. The evaporator was operated by steam (80% quality) at 143.27 kPa. The vacuum in the evaporator allows the juice to boil at 80 ° Celsius. the specific heat of the Ecer material is 4.1 KJ / (kg degrees Celsius) and the concentrate product is 3.1 KJ / (kg degrees Celsius). Count it a. Steam demand rate = b. Steam economy if Condensate temperature is released at 75 ° Celsius =