ASHRAE research project RP-1311 concluded with the creation of simulation models, the ASHWAT models, for complex fenestration systems (CFS) – glazing systems with attachments such as shades and insect screens. In these models, radiant flux – solar beam/diffuse or longwave –is on a layer-to-layer basis. ASHWAT also takes into account the convective heat transfer between the CFS layers. Methods to obtain convection coefficients for glazing cavities are well established, even for a cavity that includes a venetian blind. In this paper, a new numerical technique is applied to generate new convection coefficients for complex fenestration systems.

Recent work has been conducted to characterize the air-side heat transfer and pressure drop performance of heat exchangers with slit and louver fins and tube outer diameters ranging from 3-5 mm. These newly developed correlations have been implemented into a heat exchanger simulation tool to predict performance, enable design, and conduct detailed analysis. An optimization study was conducted using a Multi-Objective Genetic Algorithm (MOGA) technique. This paper highlights the benefits of reducing tube diameters in tube-fin heat exchangers and illustrates an approach to design and optimize heat exchangers to meet a wide range of design criteria.

Sinusoidal wavy fins can help enhance heat transfer in plate-fin heat exchangers and thus improve the performance of compact heat exchangers in many different industrial areas like air-conditioning, heating, and waste-heat recovery. Besides increasing the surface area density of the heat exchanger, implementing sinusoidal wavy fins in plate-fin heat exchangers can also augment the convection heat transfer coefficient by generating swirls in the trough regions of the channels. In this study, single-phase, periodically developed, laminar forced convection in sinusoidal wavy-plate-fin channels is considered, with the corrugated plates subjected to uniform wall temperature.

Offset strip fins are used to increase the heat transfer coefficient as well as heat transfer area in compact heat exchangers. The formation and disruption of boundary layer takes place periodically in offset strip fins yielding high heat transfer coefficient, especially near the leading edge of each periodic portion. To characterize these effects, a computational study of flow and heat transfer in offset strip channels is performed. The Reynolds number in the laminar range (10 < Re < 2000) is considered and a range of Prandtl number is considered. A parametric study is also performed.