This paper describes various aspects of the design methodology and heat transfer calculations for an elevated linear absorber. The absorber is a part of the linear Fresnel reflector solar concentrator system, in which hot fluid is generated. The design of the absorber is an inverted trapezoidal air cavity with a glass cover enclosing a multi tube absorber. In a trapezoidal cavity absorber, a set of linear multi tube absorber with plate(named as “plane surface”) and without plate(named as “tube surface”) underneath are considered. An analytical simulation is done for different gaps between the tubes and for different depths of the cavity. A better design of the absorber is found out to maximize the heat transfer rate supplied to the absorber tube fluid. Also, the experimentally obtained overall heat loss coefficients are compared with the analytical values for the considered arrangements of absorber set up and results are discussed in details. This paper describes various aspects of the design methodology and heat transfer calculations for an elevated linear absorber. The absorber is a part of the linear Fresnel reflector solar concentrator system, in which hot fluid is generated. The design of the absorber is an inverted trapezoidal air cavity with a glass cover enclosing a multi tube absorber. a set of linear multi tube absorber with plate (named as “plane surface”) and without plate (named as “tube surface”) underneath are considered as is the difference between the tubes and for different depths of the cavity. A better design of the absorber is found out to maximize the heat transfer rate supplied to the absorber tube fluid. heat loss coefficients are compared with the analytical values ​​for the considered arrangements of absorber set up and results are discussed in details.