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Untapped geothermal sites in the United States havethe estimated potential to deliver
(a) Assuming the brine has the properties of water, determine the required brine flow raw, the requiredeffectiveness of the heat exchanger, and therequired heat transfer surface area. The overall heat transfer coefficient is
(b) Over time, the brine fouls the heat transfer surfaces, resulting in
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Fundamentals of Heat and Mass Transfer
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- A single-stage fluid with a mass flow rate of 2.5 kg / s and a heat capacity of 1800 J / kg-K is cooled from 175 ° C to 75 ° C, using a single house fluid with a mass flow rate of 2kg / s and a heat capacity of 2250 J / kg-K during the process. The cold fluid heats from 50C to 150C. For this process, you would prefer to use 1 boiler 2 tube pass heat exchanger or 2 boiler 4 tube pass heat exchanger. Show it mathematicallyarrow_forwardIn a pipe-boiler type heat exchanger, when ho=500W/m2-K and hi=1500W/m2-K, when the mass flow rate on the pipe side is increased by 30%, how should the mass flow rate on the boiler side be changed, provided that the total heat transfer coefficient remains constant?arrow_forwardA. Calculate the thermal efficiency of a Rankine cycle in which the steam is initially dry saturated at 2 Mpa and the condenser pressure 7kN/m². Express this efficiency as a percentage of a Carnot cycle efficiency of the same limits of temperature. B. If the steam leaves the boiler at 350°C with the same pressure of the boiler and condenser given above. Explain why the Rankine efficiency in (A) is less than in (B), and why the ratio of efficiencies of the respective Rankine and Carnot is grater.arrow_forward
- Steam enters the turbine of a cogeneration plant at 6 MPa and 550°C. One-third of the steam is extractedfrom the turbine at 1400 kPa pressure for process heating. The remaining steam continues to expand to20 kPa. The extracted steam is then condensed and mixed with feedwater at constant pressure and themixture is pumped to the boiler pressure of 6 MPa. The mass flow rate of steam through the boiler is 30kg/s. Disregarding any pressure drops and heat losses in the piping, and assuming the turbine and thepump to be isentropic, determine (a) the net power produced, (b) the utilization factor of the plant, (c)the exergy destruction associated with the process heating, and (d) the entropy generation associatedwith the process in the boiler.Assuming a source temperature of 1000 K and a sink temperature of 298 K.arrow_forwardConsider operation of a single pass cross-flowheat exchanger with water (cp = 4193 J/kg·K) (mixed) andmethanol (cp = 2577 J/kg·K) (unmixed). Water entering andexiting the heat exchanger at 90°C and 60°C, respectively, isused to heat the methanol initially at 10°C. The overall heattransfer coefficient and the total heat transfer rate are estimatedto be 650 W/m2·K and 250 kW, respectively. In orderto achieve an effectiveness of at least 0.5, (a) what would be the mass flow rate of water and heat exchanger surface area?(b) If the mass flow rate of water is changed within 630% ofthat determined in part (a) with the same surface area (As),plot the variation of heat transfer rate, methanol exit temperature,overall heat transfer coefficient and the effectiveness ofheat exchanger with respect to change in the water flow rate.arrow_forwardWhat type of heat exchanger is a waste heat boiler? Is it a regenerator or a recuperator? Choose only between the two.arrow_forward
- A Cascade refrigeration system using R-410A and a heat exchanger is operating an evaporator with a capacity of 8 tons and temperature of -30°C. If the heat exchanger produces 1.0 Mpa and the condensing temperature is 50°C, determine the COP and the refrigerating efficiency of the system. Draw the schematic diagram of the system and assume ideal conditions.arrow_forwardThe radiator in an automobile is a cross-flow heat exchanger (UAs = 10 kW/K) that uses air (cp = 1.00 kJ/kg·K) to cool the engine-coolant fluid (cp = 4.00 kJ/kg·K). The engine fan draws 30°C air through this radiator at a rate of 10 kg/s while the coolant pump circulates the engine coolant at a rate of 5 kg/s. The coolant enters this radiator at 80°C. Under these conditions, the effectiveness of the radiator is 0.4. Determine (a) the outlet temperature of the air and (b) the rate of heat transfer between the two fluids.arrow_forwardUsing that information and this table For the average monthly rate of geothermal heat available, determine, for the real case: in a tabular format and show sample calculation for one month. the necessary monthly average mass flow rate (in kg/s) of the refrigerant that must be pumped through the heat exchanger to collect the thermal energy from the available geothermal hot water flow rate if the hot water was cooled by 5°C. What should be the flow capacity (in kg/s) of feed pump of the ORC heat engine that you are designing and the monthly average net electric power generation capacity (in kW). 2. the monthly average net electric power generation capacity (in kW) and yearly average net electrical power generation capacity (in kW).arrow_forward
- Steam enters the turbine of a cogeneration plant at 6 MPa and 550 degrees * C . One-third of the steam is extracted from the turbine at 1400 kPa pressure for process heating. The remaining steam continues to expand to 20 kPa. The extracted steam is then condensed and mixed with feedwater at constant pressure and the mixture is pumped to the boiler pressure of 6 MPaThe mass flow rate of steam through the boiler is 30 kg/s. Disregarding any pressure drops and heat losses in the piping, and assuming the turbine and the pump to be isentropic, determine (a) the net power produced(b) the utilization factor of the plant, (c) the exergy destruction associated with the process heating, and (d ) the entropy generation associated with the process in the boiler. Assuming a source temperature of 1000 K and a sink temperature of 298 Karrow_forwardHot fluid enters at a flow rate of 3 kg/sec with an inlet temperature of 150 C while cold fluid enters 5 kg/sec and with an inlet temperature of 60 C. Determine the maximum heat transfer that can happen during the heat exchange process? Take specific heat value of the fluid as 2000 J/(kgC) A) 1 MW B) 150 kW C) 540 kW D) not sufficient information E) none of the above 900 kWarrow_forwardSteam with 80% quality is being used to heat a 40% total solids tomato purée as it flows through a steam injection heater at a rate of 400 kg/h. The steam is generated at 169.06 kPa and is fl owing to the heater at a rate of 50 kg/h. Assume that the heat exchanger effi ciency is 85%. If the specifi c heat of the product is 3.2 kJ/(kg K), determine the temperature of the product leaving the heater when the initial temperature is 50C. Determine the total solids content of the product after heating. Assume the specific heat of the purée is not infl uenced by the heating process.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning