On June $15$ from $3$:$00$ to $4$:$00$ pm in Jerusalem, Palestine $($at $31\mathrm{.}7\backslash$deg N latitude$),$ a flat$-$plate collector

$(2\backslash$times $5$ m$)$ faces south, tilted $48\backslash$deg from horizontal received a solar radiation $($Gt$)$ of $1200$ W$/$m$2$

on its

surface at an ambient temperature of $17\backslash$deg C$.$ Given the following information, estimate:

Overall heat loss coefficient $=7\mathrm{.}2$ W$/$m$2$

$-\backslash$deg C

Water inlet temperature $=32\backslash$deg C

Mass flow rate through the collector $=0\mathrm{.}23$ kg$/$s

Tube inside convection heat transfer coefficient $=255$ W$/$m$2$

$-$K

Single glazing cover with n$=1\mathrm{.}526$ and KL $=0\mathrm{.}037$

Absorber plate is selective with $\backslash$alpha n $=0\mathrm{.}94,$ thickness $=0\mathrm{.}45$ mm and $\backslash$tau r $=0\mathrm{.}90$

Heat removal factor $=0\mathrm{.}85$

a$)$ The inclination angle $(\backslash$delta $)$

b$)$ The incident angle $(\backslash$theta $)$

Faculty of Engineering

Mechanical Engineering Department

Renewable Energy Engineering

Final Exam: Solar thermal systems

Instructor Name: Dr$.$ Hassan Sawalha $($Manasra$)$ Student Name:

Academic Year:$2023/2024$ Registration Number:

Semester: Fall Total Exam Mark: $45$

Credit Hours: $3$ Exam Weight: $45$

Date: Tuesday, Jan. $2$ Exam Duration: $90$ minutes nd$,2024$

Questions Q$1$ Q$2$ Total

Points $202545$

SO$$s $12$

Grade

c$)($a$/$an$)$

d$)\backslash$tau $\backslash$alpha

e$)(\backslash$tau $\backslash$alpha $)$

f$)$ The useful energy gain of the collector