A dc transformer is supplied with electric power at 230 watts with an input voltage of 220 volts. The transformer output is 1.9 amps at 110 V. The heat transfer surface area for the transformer can be modeled as a 10 cm x 10 cm x 10 cm cube. The convection heat transfer coefficient for the transformer is hconv=6 W/m².K. (a) Determine the input current to the transformer, in amps. (b) Determine the rate of heat transfer from the transformer at steady-state operation conditions, in W. (c) Determine the steady-state surface temperature of the transformer if the ambient air temperature is 25°C. Ans: a1075 amns << 15 gmns

A dc transformer is supplied with electric power at 230 watts with an input voltage of 220 volts. The transformer output is 1.9 amps at 110 V. The heat transfer surface area for the transformer can be modeled as a 10 cm x 10 cm x 10 cm cube. The convection heat transfer coefficient for the transformer is hconv=6 W/m².K. (a) Determine the input current to the transformer, in amps. (b) Determine the rate of heat transfer from the transformer at steady-state operation conditions, in W. (c) Determine the steady-state surface temperature of the transformer if the ambient air temperature is 25°C. Ans: a1075 amns << 15 gmns

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

Related questions

Q: thermal heat pump with a coefficient of performance of 1.3 supplies a building with 48000 BTU/hr of…

A: Given:COP of heat pump=1.3Heat supplied, Qa=48000 BTU/hrRate, R=$0.20/KWh

Q: Question 6: Find the required length of a 5 cm-diameter tube to heat water from an inlet temperature…

A: Given data: Diameter of the pipe, d=5 cm=0.05 m Let 'L' be the length of the pipe. Inlet temperature…

Q: Refrigerant vapor rejects 70 kW of heat as it passes through an air-cooled condenser. The condenser…

Q: The inner and outer surfaces of a 25-cm-thick wall are at 27 oC and 45 oC, respectively. The outer…

Q: МЕСН 2344 QUIZ 3 Buring steady-state operation, a gearbox receives 60 kw through the input shaft and…

A: Given data: Heat received by the gear box = 60 kW Heat transfer coefficient = 170 W/m2.K Outside…

Q: A home located in Texas, U.S. use 14000 kWh of electricity in 2021. The home is powered by a diesel…

A: Since you have asked multiple questions, we will solve the first question for you. If you want any…

Q: costs 8 cents per kW-hr, determine the minimum theoretical operating cost to heat the house for 24…

Q: Inner radius 15 cm, outer radius 20 cm and k = 15 W / m ∙ Consider a pipe with oC. Heat transfer…

Q: The Ocean Thermal Energy Conversion (OTEC) system in Hawali utilizes the surface water and deep…

Q: An engineer designs a heat engine using flat-plate solar col-lectors. The collectors deliver heat at…

A: Before finding the efficiency we need to convert the value of temperature from °C to K.

Q: f 7.59 kg/s. If conde

Q: yo to analysis syster onditioning system. Given that the refrigerant is R-134a. Tabl ollection on…

Q: A room is heated by an electrical space heater operating at 1500W and its temperature is 800 C. The…

A: Given: space heater Q˙ = 1500 W Temperature(Th) = 800°C Convective heat transfer coefficient (h)= 6…

Q: W НЕ Q: Ta

Q: Determine the conduction heat transfer INSULATOR rate through the wall. Ts2 Ts1 T32 M H L INSULATOR…

A: Given:

Q: PR and As shown In the figure, an exterior wall of a bullding nas an average thermal conductivity of…

Q: a. Find the overall heat transfer coefficient = Answer W / m² ° C. b. Heat transfer rate per meter…

A: The temperature of steam flowing inside the pipe is, Ti=160 °C. Inner radius of the pipe is, r1=50…

Q: Consider a wall consisting of two layers, A and B, with the following properties: = 1.5 W/m.K; LA =…

Q: Consider a pipe with an inner radius of 15 cm, an outer radius of 20 cm, and k = 15 W / m ∙ oC. The…

Q: 1. Is it possible to operate a heat engine with only a high-temperature heat reservoir??

A: Since we only solve one question at once, we will answer the first one. Please resubmit the question…

Q: SUPPOSE THE AMBIENT TEMPERATURE IS 20degrees CELSIUS, AND THE HOT RESERVOIR CONSISTS OF A SPHERICAL…

Q: b. A slab of stone of area (3600 + R) cm² and thickness 10 cm is exposed on the lower surface to…

A: Draw diagram of slab for better understanding

Q: The Ocean Thermal Energy Conversion (OTEC) system in Hawai utilizes the surface water and deep water…

Q: 5.) Does a refrigerator full of food consume more power if the room temperature is 200C than if it…

Q: SANAE IV, a research station of The South African National Antarctic Programme (SANAP), is located…

A: Given: The temperature of science lab, T2 = 307.8 K The heat supplied to lab, Q2 = 17360 J The work…

Q: Determine the maximum possible thermal efficiency achievable by a heat engine.

A: Given: T1=20oC T2=6oC TO determine: The maximum possible thermal efficiency achievable by the heat…

Q: An electric resistance heater is used to provide space heating at an efficiency level of 100%. The…

A: Space heating demand: 1137.8 MBHConversion factor: 1 MBH = 1000 BTU/hElectricity cost: $0.13 per…

Q: 1.2 A concrete wall in a factory located in Canada has a thickness of 0.1 metres. The wall is…

Q: You need an apartment for rent and as shown in the figure, you can see that the 3rd floors of each…

Q: is |Q|=-kA(dt/dx) the law that defines the rate of heat transfer by conduction (fourier's law of…

A: Q=-kAdt/dx is the Fourier's law of heat conduction which defines the rate of heat transfer by…

Q: Refrigerant vapor rejects 70 kW of heat as it passes through an air-cooled condenser. The condenser…

Q: An electrical circuit consisting of six resistors with a power supply. Apply Thevenin's theorem…

A: KIRCHHOFFS VOLTAGE LAW:It states that the algebraic sum of voltages and their voltage drops are…

Q: The eyclic device can be

A: Given data; T1=1000 KT2=500 KT3=300 KQ1=Q2=Q3=100 KJ=50 KJ=60 KJ respectiveley

Q: A heating system must maintain the interior of a building at TH = 20°C when the outside temperature…

Concept explainers

Conduction and Convection

When energy travels from one object to another it is said to have undergone heat transfer. Heat transfer is nothing but the transfer of thermal energy or internal energy from one thing to another, like e.g., when a vessel with water, kept on top of a burner, heats up because of the flame underneath it.

Question

Problem 23.1
A dc transformer is supplied with electric power at 230 watts with an input voltage of 220 volts. The
transformer output is 1.9 amps at 110 V. The heat transfer surface area for the transformer can be
modeled as a 10 cm x 10 cm x 10 cm cube. The convection heat transfer coefficient for the transformer is
hconv=6 W/m².K.
(a) Determine the input current to the transformer, in amps.
(b) Determine the rate of heat transfer from the transformer at steady-state operation conditions,
in W.
(c) Determine the steady-state surface temperature of the transformer if the ambient air
temperature is 25°C.
Ans: a) 0.75 amps ≤ |I| ≤ 1.5 amps
b) 15 W ≤ ≤ 25 W
c) 90°C ≤ |T| ≤ 100°C (for 5 sides w/ heat transfer)

Expert Solution

This question has been solved!

Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.

This is a popular solution!

SEE SOLUTION Check out a sample Q&A here

Step 1: Given

VIEW

Step 2: Part A,B and C

VIEW

Solution

VIEW

Trending now

This is a popular solution!

Step by step

Solved in 3 steps with 2 images

SEE SOLUTION Check out a sample Q&A here

Knowledge Booster

Learn more about

Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.

Similar questions

A solar system operates under the following conditions: Solar radiation 1100 W/m2, Specific collector gain qcoll 600 W/m2, specific heat capacity fluid cp 0,011KWh/kg.K, density fluid 1000 kg/m3, total collector surface area 20 m2. The solar system worked in winter day and you need hot water for shower.(The hot water temperature 45 degree C, cold water temperature 15 degree C). The volume of flow of this solar system is
In a room (6*5*4 m), if you have a thermal mass in a concrete floor with a thickness of 15 cm (concrete density = 2,250 kg/m3 and SHC= 0.21 kCal/oC.kg), knowing that the ∆Tswing = 4 oC, the occupant gains 3 kWhr/day, the equipment gains =5.5 kWhr/day and the lighting gains = 2.5 kWhr/day, the total heat loss = 30,865 Whr/day. Find the thermal capacity of the floor? What is the quantity of energy we can store in the floor in BTU? What will be the solar gain needed in order to store the previous energy and cover the day requirements?
Steam at 140 ° C flows in a pipe having an inner radius of 50 mm and an outer radius of 55 mm. The convective heat transfer coefficient between the steam and the inner pipe wall is 2500 W / (m² ° C). The outer surface of the pipe exposed to ambient air is 20 ° C with a convective heat transfer coefficient of 10 W / (m² ° C). Assuming steady state, calculate the rate of heat transfer per meter of pipe from steam to air. Assume that the thermal conductivity of stainless steel is 15 W / (m ° C.). Steps of work according to example 4.16 Singh. a. Find the overall heat transfer coefficient = Answer W / m² ° C. b. Heat transfer rate per meter of pipe = Answer W / m.
1. Humans are able to control their rates of heat production and heat loss to maintain a nearly constant core temperature of Te = 37°C under a wide range of environmental conditions. This process is called thermoregulation. From the perspective of calculating heat transfer between a human body and its surroundings, we focus on a layer of skin: fat, with its outer surface exposed to the environment and its inner surface at a temperature slightly less than the core temperature, T = 35°C = 308 K. Consider a person with a skin/fat layer of thickness L = mm and effective thermal conductivity k = 0.3 "- The person has a surface area A = 1.8 m? and is dressed in a bathing suit. The m· K emissivity of the skin is ɛ = 0.95. a). When the person is in still air at T = 282 K, what is the skin surface temperature and rate of heat loss to the environment? Convection heat transfer to the air is characterized by a free convection coefficient of h 2 m2 -K b). When the person is in water at T = 282,…
IP Heat Transport in the Human Body The core temperature of the human body is 37.0 ∘C∘C, and the skin, with a surface area of 1.40 m2m2, has a temperature of 34.0 ∘C∘C. Find the rate of heat transfer out of the body under the following assumptions: (i) The average thickness of tissue between the core and the skin is 1.20 cmcm; (ii) the thermal conductivity of the tissue is that of water. Express your answer using two significant figures. Without repeating the calculation of part A, what rate of heat transfer would you expect if the skin temperature were to fall to 31.0 ∘C∘C? Express your answer using two significant figures.
< Q5: Determine the COP of a refrigerator which removes heat from the food compartment at a rate of 6000000 J/h for each 1200 W of power it consumes. A: 1.35 OB: 1.36 C: 1.37 D 1.38
Refrigerant vapor rejects 70 kW of heat as it passes through an air-cooled condenser. The condenser has an air-side area of 210 m2 and, based on this area, has an overall heat transfer coefficient of 0.037 kW/m2∙°C. Cooling air flows at a rate of 7.59 kg/s. If condensation of the refrigerant occurs at 55°C, what is the inlet temperature (in °C) of the air? Take the specific heat of air to be 1.02 kJ/kg∙°C.
Refrigerant vapor rejects 70 kW of heat as it passes through an air- cooled condenser. The condenser has an air-side area of 210 m2 and based on this area, has an overall heat transfer coefficient of 0.037 kW/m2.°C. Cooling air flows at a rate of 7.59 kg/s. If condensation of the refrigerant occurs at 55°C, what is the outlet temperature (in °C) of the air? Take the specific heat of air to be 1.02 kJ/kg.°C.
b. A slab of stone of area (3600 + R) cm² and thickness 10 cm is exposed on the lower surface to steam of (100 + R )° C. A block of ice at 0° C rests on upper surface of the slab. In one hour 4.8 kg of ice is melted. Calculate the thermal conductivity of the stone. Consider the specific latent heat of ice is (3.36 + R) x10° Joules. R=76
8. Four 20-watt lamps and two ½ - hp motors of the forced-draft evaporators are installed inside a refrigerated space. The lamps are usually switched on 16 hours per day. Calculate the heat load component of the lamps and the motors, in Btu/day.
What is the payback time on a solar hot-water system that cost$ 5,000? Assume the system reduces electrical energy consumption by 4,000 kWhr each year and ilectricity costs 16 cents per kWhr. O 8 years O 4 years O 12 years O 15 years.
As they work, computers emit heat. Do you have any questions concerning computer air conditioning?