Problem 04.038 Energy balance for an electrical radiator - A 40-L electrical radiator containing heating oil is placed in a 50 m³ room. Both the room and the oil in the radiator are initially at 10°C. The radiator with a rating of 2.4 kW is now turned on. At the same time, heat is lost from the room at an average rate of 0.35 kJ/s. After some time, the average temperature is measured to be 20°C for the air in the room, and 70.0°C for the oil in the radiator. Taking the density and the specific heat of the oil to be 950 kg/m³ and 2.2 kJ/kg °C, respectively, determine how long the heater is kept on. Assume the room is well sealed so that there are no air leaks. The gas constant of air is R = 0. 287 kPa m³/kg K (Table A-1). Also, c = 0.718 kJ/kg-K for air at room temperature (Table A-2). Oil properties are given to be p = 950 kg/m³ and Cp=2.2 kJ/kg. °C (Round the final answer to three decimal places.) Room 10°C Q Radiator ces The heater is kept on for min.

Problem 04.038 Energy balance for an electrical radiator - A 40-L electrical radiator containing heating oil is placed in a 50 m³ room. Both the room and the oil in the radiator are initially at 10°C. The radiator with a rating of 2.4 kW is now turned on. At the same time, heat is lost from the room at an average rate of 0.35 kJ/s. After some time, the average temperature is measured to be 20°C for the air in the room, and 70.0°C for the oil in the radiator. Taking the density and the specific heat of the oil to be 950 kg/m³ and 2.2 kJ/kg °C, respectively, determine how long the heater is kept on. Assume the room is well sealed so that there are no air leaks. The gas constant of air is R = 0. 287 kPa m³/kg K (Table A-1). Also, c = 0.718 kJ/kg-K for air at room temperature (Table A-2). Oil properties are given to be p = 950 kg/m³ and Cp=2.2 kJ/kg. °C (Round the final answer to three decimal places.) Room 10°C Q Radiator ces The heater is kept on for min.

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

(c) A resistant heater jacket 6.5kW is wrapped around a water bath for 240 minutes to raise the water temperature to the desired temperature level. Determine the amount of electric energy used in both kWh and kJ.
In a commercial water heater, 80 L/min of water is heated from 20° C to 60° C . Calculate the amount of energy required per hour.
Consider a conventional piston-cylinder system. Compute the work required to compress air to 0.2 m3 initially contained under atmospheric pressure and in a volume of 0.5 m3. Consider three cases: a) the processes is isobaric: b) the process is adiabatic: c) the process is isothermal:
No Handwriting please
1. A room is filled with saturated steam at 100°C. Now a 5-kg bowling ball at 25°C is brought to the room. Heat is transferred to the ball from the steam, and the temperature of the ball rises to 100°C while some steam condenses on the ball as it loses heat (but it still remains at 100°C). The specific heat of the ball can be taken to be 1.8 kJ/kg · C. Solve for the mass of steam that condensed during this process. (3 DECIMAL IN FINAL ANSWER PLS)
A piston-cylinder device initially contains CO2 at 200 kPa and 400°C and the total enclosed volume is 300 litres. Due to heat loss, the piston moves downwards to a position where it sits on a pair of stoppers and its final enclosed volume is 150 litres. Further heat loss leads to the pressure being reduced to 160kPa. Workout 1) the final temperature, 2) the total work done by CO2 and 3) the total heat transferred to CO2. Also make some comments on the result of heat. 4) Create a schematic p-v diagram of the process The following assumptions are to be made: CO2 is a perfect gas and its molecular mass is 44kg/kmol. The ratio of specific heat capacities, γ (gamma) is 1.3 The volume occupied by the stoppers is to be ignored. There is no leakage in the system There is no friction between the cylinder and piston walls and the piston moved slowly at the same speed therefore, no acceleration. For the conversion from Celsius to Kelvin, use 273 Use 8314.5 J/kmol.K for the universal gas constant
In a given process, a heat engine requires 2500J of energy and exhausts 1200J of heat. What is its efficiency?
In a quasi-static isobaric expansion, 540 J of work are done by the gas. The gas pressure is 0.90 atm and it was originally at 15.0 L. If the internal energy of the gas increased by 70 J in the expansion, how much heat (in J) does the gas absorb?
Complete Solutions
Problem 04.037 - Energy balance for water in a piston-cylinder device An insulated piston-cylinder device contains 4.500 L of saturated liquid water at a constant pressure of 175 kPa. Water is stirred by a paddle wheel while a current of 8 A flows for 45 min through a resistor placed in the water. One-half of the liquid is evaporated during this constant-pressure process and the paddle-wheel work amounts to 400 kJ. W H₂O P= constant Wsh www Problem 04.037.a - Find source voltage Determine the voltage of the source. Use data from the steam tables. (Round the final answer to two decimal places.) The voltage of the source is V.
In a steam engine the pressure and volume of steam satisfy the equation PV1.4 = k, where k is a constant. (This is true for adiabatic expansion, that is, expansion in which there is no heat transfer between the cylinder and its surroundings.) Calculate the work done by the engine during a cycle when the steam starts at a pressure of 180 lb/in2 and a volume of 300 in3 and expands to a volume of 1000 in3.
A closed system undergoes an adiabatic process. During the process, the system operates at the same elevation and is at rest. The system internal energy between its initial and final states increased by 10kJ. Write the energy balance for this problem.