Which is the transfer of thermal energy through direct contact of particles? التوصيل conduction الإشعاع radiation...
The following three substances are placed together in thermal contact: 1) Mg = 1.0 kg gold at temperature Tg = −13 C 2) Ms = 2.0 kg silver at temperature Ts = +7.0 C 3) Mi = 0.01 kg ice at temperature Ti = 0.0 C What is the final equilibrium temperature T ? Data: specific heat of ice: Ci = 2100 specific latent heat of fusion of ice/water: Lf = 3.35 × 10^5 specific heat of gold: Cg =...
After transfer of 1.50 kJ of thermal energy to a 0.675-kg block of copper the temperature is 49.1 °C. The specific heat capacity of copper is 0.385 Jg oc1 Calculate the initial temperature of the copper. oC
(a) (iWhen is heat transfer through a fluid by conduction or by convection? For what case is the rate of heat transfer higher? How does the convection heat transfer coefficient differ from the thermal conductivity of a fluid? (ii) Explain the physical significance of Nusselt number (ii) By definition, discuss hydraulic diameter. Obtain an expression for hydraulic diameter of a circular tube of diameter, D (b) The local atmospheric pressure in Gboko, Benue State Nigeria (elevation 1610 m), is 834...
After transfer of 1.60 kJ of thermal energy to a 0.451-kg block of copper the temperature is 44.1 °C. The specific heat capacity of copper is 0.385 J g-1 °C-1. Calculate the initial temperature of the copper.
Thermal energy storage systems commonly involve a packed bed of solid spheres through which a hot gas flows when the system is being charged. In the charging process heat is transferred from the hot gas to the spheres and it increases the thermal energy stored in the spheres. Here are some variables that are important - the convection coefficient between the particle surface and the gas is h (W/m2 K) and the particle thermophysical properties are k (W/m K), Cp...
Wayne Industries has developed a revolutionary computer processor which dissipates 0.25 Watts of thermal energy through a heat sink by convection and radiation (black body) into the surroundings (20 oC). You are tasked with determining the steady-state surface temperature of the heat sink if the convective heat transfer coefficient is 5 ? /?2.? , and the heat sink has an effective area of 0.001 m2 ?
10 Amps of DC current is passed through a 10 OHM resistor in thermal contact with an 6 g block of Arbitrarium. The temperature of the block is raised by 6 K by this process. What is the specific heat of Arbitrarium? Units J/gK
The heat that is conducted through a body must frequently be removed by other heat transfer processes. For example, the heat generated in an electronic device must be dissipated to the surroundings through convection by means of fins. Consider the one-dimensional aluminum fin (thickness t 3.0 mm, width 20 cm, length L) shown in Figure 1, that is exposed to a surrounding fluid at a temperature T. The conductivity of the aluminum fin (k) and coefficient of heat convection of...
Which of the following are true about radiation of heat? Mark all that apply. The rate of energy transfer is proportional to the surface area of the object Radiation occurs when mass at one temperature transfers to a different location Radiation can transfer heat through empty space (vacuum) Radiation is a result of the collisions between molecules in two different objects at two different temperatures Which of the following characteristics describe good thermal conductors? Mark all that apply. High thermal...
Calculate the rate of energy loss due to thermal radiation from an unclothed person if the average skin temperature is 37 °C and the room temperature is 20 °C. You may sume a total surface area of 1.5 m and a skin emissivity value of 0.9. How much energy (from food) must be consumed per day to compensate for this loss? If the person is surrounded by a layer of insulation of thickness 1.0 cm with a thermal conductivity of...