LX20231211-1201

Last Name 1 Student’s Name Professor’s Name Course Number Date Part 1 Number 1: The heightened temperature within an enclosure with abundant glass windows, such as a greenhouse or parked car, stems from the greenhouse effect facilitated by the glass structure. Glass permits the transmission of sunlight, encompassing a spectrum of electromagnetic waves, predominantly in the visible light range. Once inside the enclosure, various surfaces absorb the incoming sunlight, transforming it into heat. While the glass allows sunlight to enter, it impedes the efficient escape of infrared radiation, which is the form of heat energy emitted by objects inside the enclosure as they warm up. This leads to a trapping of heat within the confined space, analogous to the greenhouse effect observed in the Earth's atmosphere, where certain gases trap heat and elevate temperatures. Furthermore, the enclosed space's limited ventilation exacerbates the temperature rise. Unlike outdoor environments that benefit from natural air circulation, an enclosure with glass windows may lack effective ventilation. The constrained airflow hinders the dissipation of accumulated heat, contributing to the overall temperature increase within the enclosure.

Last Name 2 Number 2: Carbon dioxide (CO2) is a greenhouse gas that plays a crucial role in regulating the Earth's temperature. The Earth's surface absorbs sunlight and re-emits this energy as infrared radiation. CO2 molecules in the atmosphere are particularly effective at absorbing and re- emitting infrared radiation in the wavelength range of 10 – 15 µm. Currently, the Earth's atmosphere contains a certain concentration of CO2 that allows some of the infrared radiation to escape into space, balancing the energy budget and maintaining a relatively stable climate. However, when there is an increase in the atmospheric concentration of CO2, which is often associated with human activities such as burning fossil fuels, deforestation, and industrial processes, more infrared radiation is trapped within the Earth's atmosphere. This trapped heat leads to a warming of the planet, known as the enhanced greenhouse effect. Even a small increase in CO2 concentration can have a significant impact on the Earth's climate system. The additional warming can result in changes to weather patterns, sea level rise, melting of polar ice caps and glaciers, and disruptions to ecosystems, collectively contributing to global climate change. Therefore, the sensitivity of CO2 to infrared radiation in the 10 – 15 µm wavelength range is a key factor in understanding how human-induced increases in CO2 concentration can lead to profound and far-reaching effects on the Earth's climate. Number 3: Thermal imaging cameras typically employ lenses with coatings that are transmissive to radiation in the 8 – 14 µm wavelength range, while being reflective to other wavelengths, primarily for optimal detection and imaging of infrared radiation emitted by objects at normal temperatures. This wavelength range corresponds to the peak of the thermal radiation emitted by

Last Name 4 q atm, 13-∞ = 0.10 × 800 × (1- 0.5) = 40 Wm -2 Calculate the total atmospheric irradiation heat flux: q atm, = 60 + 684 + 152 + 140 + 36 = 1076 Wm -2 B. Emissive Power (E band ) and Total Emission (E): (E band ) = εband × σ × T 4 c E 0-0.3 = 0.75 × 5.67×10 −8 × 285 4 = 280.55watts E 0.3-1.0 = 0.90 × 5.67×10 −8 × (285) 4 = 336.67watts E 1.0-8.0 = 0.20 × 5.67×10 −8 × (285) 4 = 74.86watts E 8.0-13 = 0.50 × 5.67×10 −8 × (285 )4 = 187.04watts E 13-∞ = 0.10 × 5.67×10 −8 × (285) 4 = 37.14 watts Total Emission = E = E 0−0.3 + E 0.3−1.0 + E 1.0−8.0 + E 8.0−13 + E 13−∞ = 916.491 waats C. ε eff= E σ ⋅ T c 4 = 916.491 5.67 × 10 − 8 × ( 285 ) 4 = 0.31 = 31% D. Certainly, let's proceed with solving the energy balance equation to find the cooling surface temperature ( T c): The energy balance equation is given by: q sun + q atm − E − h ⋅ ( T c− T ∞) = 0 T ∞=15°C=288K (ambient air temperature) h =5W m−2K−1 (heat transfer coefficient) q sun=800W m−2 We've already calculated q atm and E . Now we'll substitute these values into the energy balance equation and solve for T c:

Last Name 5 800 + 1076 − 916.41 − 5 ⋅ ( T c−288) = 0 − 5 ⋅ ( T c−288) = -959.59 -5 Tc + 1440 = -960 -5Tc = - 2400 Tc = 2400 / 5 Tc = 480K Now, let's find out how much cooler the surface is than the surrounding air: Δ T = T c− T ∞ = 480 − 288 = 192K Number 2: Radiation Resistance Network Assumptions: Gray Surfaces: Emissivity and absorptivity remain constant across all wavelengths. Diffuse Surfaces: Radiation is emitted and absorbed uniformly in all directions. Steady State: Temperatures remain constant over time. Exclusion of Conduction or Convection: Heat transfer occurs exclusively through radiation. Network Diagram

Last Name 7 F12 = π × arctan ( a b ¿ = π × arctan ( 0.08 0.5 ) = 0.167 rad Other view factors: F13 = 1 – F12 – F14 = 0.823 F23 = 1 – F24 = 1 F34 = 1 F14 = F41 = 0 (due to small size of can compared to grill) Steady State Temperature of Can Heat Balance Q r ad E = Q r ad o ut From grill: Qradin12 = σ × ∑G × A G × (T 4 G – T 4 C ) × F12 From ambient Qradin32 = σ × ∑C × A C × (T 4 ∞ – T 4 C ) × F32 Heat radiated out: Total ambient: Q r ad o ut = = σ × ∑C × A C × (T 4 C – T 4 ∞ ) × F23 Combing Equations: σ × ∑G × A G × (T 4 G – T 4 C ) × F12 + σ × ∑C × A C × (T 4 ∞ – T 4 C ) × F32 Solving for T C : T C = 501.3K Explosion potential:

Last Name 8 Cooking spray cans commonly include a flammable propellant and are engineered to rupture at temperatures approximately reaching 450°C. Consequently, with the can's temperature at 501.3 K, surpassing the explosion threshold, it is probable that the can would detonate Convective Cooling Heat Balance: Q r ad E + Q c onv E = Q r ad o ut Heat transfer coefficient H = 10 w m 2 K A c = π × D c × H c = 0.0357m 2 Convective heat transfer: Q c onvin = hA c