A finned-tube heat exchanger is used as an air-conditioning condenser. During a steady state operation, refrigerant in the tubes remains 2-phase state throughout the heat exchanger at the condensing temperature 67 °C. Air enters the condenser at inlet temperature 22 °C and air mass flow rate is 0.7 kg/s. Refrigerant-side convection thermal resistance and tube wall conduction resistances are negligible. Airside total surface area is 8 m² and overall surface efficiency is 0.75. Airside average convection coefficient is 102 W/(m²K). The specific heat of air is 1,006 J/(kgK). Determine the heat transfer rate in W.

A finned-tube heat exchanger is used as an air-conditioning condenser. During a steady state operation, refrigerant in the tubes remains 2-phase state throughout the heat exchanger at the condensing temperature 67 °C. Air enters the condenser at inlet temperature 22 °C and air mass flow rate is 0.7 kg/s. Refrigerant-side convection thermal resistance and tube wall conduction resistances are negligible. Airside total surface area is 8 m² and overall surface efficiency is 0.75. Airside average convection coefficient is 102 W/(m²K). The specific heat of air is 1,006 J/(kgK). Determine the heat transfer rate in W.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

Counterflow to cool the oil in the lubrication system of a large industrial gas turbine. A double-pipe heat exchanger is used. Coolant flowing through the inner pipe (Cp=4178) J/kg.°C) and oil flowing through the ring channel (Cp=2005.5 J/kg.°C) mass flow rates are 0.2 and 0.4, respectively kg/s. Oil enters the heat exchanger at 60 oC and leaves at 40 oC. Water inlet temperature 30 is oC. The heat transfer coefficient on the ring side is 500 W/m2K. Diameter of thin-walled inner tube is 25 mm, the inner diameter of the outer ring is 45 mm. Pollution resistance in the inner pipe where city mains water is used It is 0.000176 m2K/W. The deposit on the oil side is negligible. a) The heat transfer coefficient in the inner pipe b) Total heat transfer coefficient, c) Calculate the length of the heat exchanger. d) If a 4 m long hairpin is used in the heat exchanger, the required number of hairpins set.
! Required information Consider a water-to-water counterflow heat exchanger with these specifications. Hot water enters at 70°C while cold water enters at 20°C. The exit temperature of the hot water is 15°C greater than that of the cold water, and the mass flow rate of the hot water is 50 percent greater than that of the cold water. The product of heat transfer surface area and the overall heat transfer coefficient is 2200 W/K. Take the specific heat of both cold and hot water to be cp= 4180 J/kg.°C. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. Cold water 20°C Hot water 40 °C Th, in Determine the effectiveness of the heat exchanger. The effectiveness of the heat exchanger is 0.72 *
P7.5 P7.5 A single-pass evaporator of a water chiller has 100 horizontal copper tubes of inner diameter 15mm and wall thickness 1.5mm through which water flows with a total mass flow rate of 1.8 kgs. Refrigerant 134a undergoes pool boiling at 2°C on the outer surface of the tubes. The water is cooled from 14°C to 6°C. The water-side and refrigerant-side heat transfer coefficients are 1100 Wm 2K and 980 Wm ²K¹ respectively. Calculate (i) the overall heat transfer coefficient based on the inner tube area, (ii) the LMTD (iii) the effectiveness of the evaporator, and (iv) the length of a tube. [Answers: (i) 567 Wm ²K¹, (ii) 7.28°C, (iii) 0.67, (iv) 3.13m]
Consider the steady-state counterflow heat exchanger shown below. There are separate streams of air and water, and each stream experiences no noticeable change in pressure. Stray heat transfer with the surroundings and changes in kinetic and potential energy can be ignored. For the air, the ideal gas model can be applied and Rair = 0.287- For the operating conditions provided on kg-K the figure, determine: a. The temperature of the air at the outlet of the heat exchanger, T4, in [K] b. The rate of heat transfer between the air and the water, in [kW; , c. The rate of entropy production for the heat exchanger, in [kW/K] kg msteam = 12 P1 = 3 bar X1 = 1 P2 = P1 T2 = 200 P3 = 1 bar T3 = 1100 K P4 = P3 T, =? mair kg = 3.29
Q2// A parallel - feed double - effect evaporator with equal vaporized for both, are fed with 5 Kg/s liquor with 10 percent for each effect. The overall heat transfer coefficients are 1.25 and 1.7 KW / m². K respectively. Steam is feed at 1.8630 bar and the second effect operates at 0.2856 bar. If the mass fraction from the 1st effect was 40 percent, What will be the total concentrated liquid from both? And compute the Temperature distribution for the system. Cp=4.18kJ/kg.k
53.1 64.4 68.6 489 523 atio of 3 (i.e 581 613 659 ge turbine ir is 10 bar reases its t which increa ssure ratio 18.7 21.4 24.4 30.2 37.9 44.5 = 0.287 kJ/k 683 711 744 773 808 er system as foll re of the air is 4 K. > first turbine ha e back up to 90 pic efficiency of !) in kW: 12 >erfectly isentropic (i.e. T') in K:
A heat pump cycle using water as the working fluid consists of a compressor, a condenser, an expansion valve, and an evaporator. Saturated vapor with mass flow rate of 1 kg/s at 0.5 MPa (state 1) enters the condenser and leaves it as saturated liquid at the same pressure (state 2). The pressure in the evaporator is 0.01 MPa. The condenser and the evaporator processes are isobaric. The compressor is adiabatic and reversible. The valve is adiabatic. A. List all the known information and assumptions. B. Determine the heat output of the condenser (QH) C. Determine the heat input of the evaporator(Qc) D. Determine the coefficient of performance of the heat pump. E. Determine the coefficient of performance of a Carnot heat pump running between the same temperatures TH and TC at the evaporator and condenser. F. Calculate the entropy generation in the compressor. G. Draw the TS diagram for the cycle on paper. (Hint: you must calculate T1, T2, T3, T4, h1, h2, h3, h4, s1, s2, s3, s4, and draw…
Superheated steam from the boiler expands in the turbine from inlet pressure p₁ of 50 bar and temperature 7 of 487 °C to condenser pressure p2 of 18 kPa. In the condenser, the steam condenses to saturated water. The isentropic efficiency of the turbine ns is 78.0 %. The mass flow of steam 9m,h is 140 kg/s. In the boiler, heat flow rate to the circulating fluid (water/steam) is 458 MW. Read from h,s-diagram and calculate: 1. Enthalpy of the superheated steam h kJ/kg (with zero decimal accuracy) 2. Enthalpy of the steam at turbine outlet after isentropic expansion h₂s kJ/kg (with zero decimal accuracy) 3. Enthalpy of the steam at turbine outlet h₂ kJ/kg (with zero decimal accuracy) 4. Turbine power Pt MW (with one decimal accuracy) 5. Steam content at the turbine outlet X2 kJ/kg (with two decimal accuracy) 6. Enthalpy after condenser h3 kJ/kg (with zero decimal accuracy) 7. Thermal power of condenser Qc 8. Thermal efficiency of the plant n MW (with one decimal accuracy) % (with one…
Q.2. Air enters a steady-flow heat exchanger with a mass flow rate of 2 kg/s as shown in Figure. Determine (a) the rate of heat transfer to the air in the heat exchanger, (b) the power output from the turbine assuming no heat loss, and (c) the velocity at exit from the nozzle. (Cp atr = 1.005 kJ/kg. K) T=600 C T- 12 C V=3 m/s Air Нeat v-3 m/s Exchanger Turbine T= 200 C V - 25 m/s T= 160 C Nozzle
Hot water (Cp= 4.188 kJ/kg.K) with mass flow rate of 2.5 kg/s at 100 C enters a thin-walled concentric tube counterflow heat exchanger with a surface area of 23 m, and an overall heat transfer coefficient of 1000 W/m^2K. Cold water (Cp= 4.178 kJ/kg.K) with mass flow rate of 5 kg/s enters the heat exchanger at 20 C. After a period of operation, the overall heat transfer coefficient is reduced to 500 W/m^2K determine the fouling factor that caused the reduction in the overall heat transfer coefficient.
Homework: A counterflow heat exchanger is located between a collector and a storage tank. The fluid in the collector side is a water-glycol mixture with cp=3840 J/kg. °C and a flow rate of 1.35 kg/s, whereas the fluid in the tank side is water with a flow rate of 0.95 kg/s. If the UA of the heat exchanger is 5650 W/°C, the hot glycol enters the heat exchanger at 59°C, and the water from the tank at 39°C, a) estimate the heat exchange rate; b) if FRUL is 5.71 W/m².°C and collector area is 16 m², what is the ratio FR/FR?
Using 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).