The Abstract - Text Analysis

"Major problems of the arid region are transportation of agricultural products and losses due to spoilage of the products, especially in summer."

This sentence gives the general problem the research is attempting to help solve (rather than the specific research problem) in order to provide a rationale for the research.

"This work presents the performance of a solar drying system consisting of an air heater and a dryer chamber connected to a greenhouse. The drying system is designed to dry a variety of agricultural products." the performance of a solar drying system consisting of an air heater and a dryer chamber connected to a greenhouse. The drying system is designed to dry a variety of agricultural products."

This part of the abstract gives the main objective of the research.

"The effect of air mass flow rate on the drying process is studied."

Here the authors give the parameter they will be focusing on in order to measure the effect of air mass flow rate on the drying process. Their research problem, therefore, is to find out the effect of air mass flow rate on the drying process. 

"Composite pebbles, which are constructed from cement and sand, are used to store energy for night operation. The pebbles are placed at the bottom of the drying chamber and are charged during the drying process itself. A separate test is done using a simulator, a packed bed storage unit, to find the thermal characteristics of the pebbles during charging and discharging modes with time. Accordingly, the packed bed is analyzed using a heat transfer model with finite difference technique described before and during the charging and discharging processes."

This part of the abstract summarizes the methodology used.

"Graphs are presented that depict the thermal characteristics and performance of the pebble beds and the drying patterns of different agricultural products. The results show that the amount of energy stored in the pebbles depends on the air mass flow rate, the inlet air temperature, and the properties of the storage materials."

Here we are told in what form the results are presented, and the main findings.

"The composite pebbles can be used efficiently as storing media."

Finally, we are presented with the main conclusion of the research. 

"The long-term performance of various systems was determined and the economic aspects of solar hot water production were investigated in this work."

Here the authors present the objectives of their research (and by implication their research problem, i.e. the long-term performation and the economic aspects are unknown and need to be found).

"The effect of the collector inclination angle, collector area and storage volume was examined for all systems, and various climatic conditions and their payback period was calculated."

Here we are told what was studied and calculated, i.e. we are given a very brief summary of the methodology. 

"It was found that the collector inclination angle does not have a significant effect on system performance. Large collector areas have a diminishing effect on the system’s overall efficiency. The increase in storage volume has a detrimental effect for small daily load volumes, but a beneficial one when there is a large daily consumption."

This part of the abstract presents the main finding (i.e. results) the authors obtained. 

"Solar energy was found to be truly competitive when the conventional fuel being substituted is electricity, and it should not replace diesel oil on pure economic grounds. Large daily load volumes and large collector areas are in general associated with shorter payback periods. Overall, the systems are oversized and are economically suitable for large daily hot water load volumes."

Finally, the main conclusions and recommendations from the research are given.