Please help with finding values T2 and T3 Of the equations

equ1=h1*D2*pi*(T2-T1-273.15)-2*pi*K23/log(D3/D2)*(T3-T2);

equ2=q_ra*(EEF_abs) - pi*D3*h34*(T3-T4) -(Bolt*pi*D3*(T3.^4-T4.^4))/(1/E3+(1-E4)*D3/(E4*D4))-2*pi*K23/log(D3/D2)*(T3-T2);

[Walter Roberson]

If we assume that there is an implicit "== 0" for both of those, then the solutions invoke the roots of a quartic -- roots of a polynomial of degree 4. Are you sure that you want the closed form solutions? They do exist but they are rather long.