Variable refrigerant flow (VRF) HVAC systems are a direct expansion (DX) heat-pump technology platform built on the standard reverse vapor compression cycle. These systems are thermodynamically similar to unitary and other common DX systems, and share many of the same components—compressor,...

Variable Refrigerant Flow (VRF) systems are fundamentally different from unitary or other types of traditional HVAC systems. The space is cooled or heated directly by circulating refrigerant to evaporators located near or within the conditioned space. The system will replace electric resistance...

The primary goal of this investigation was to provide long term laboratory test data to assess the longevity of an evaporatively-cooled condensing unit (ECCU) and to provide recommendations for operation and maintenance of the system to maintain performance and energy efficiency. A secondary...

Water cooled air conditioners have been around for several years and have an excellent performance rating out of the box, an EER of about 17. However, the experience has been that water-cooled condensers can become fouled in a very short time, circumventing their performance and become a...

Project SummaryTesting was conducted to evaluate the performance of a prototype OASys™ hybrid air conditioner, which modifies their indirect/direct evaporative cooling unit with an added direct expansion (DX) system for increased range of operation.  A test plan was developed based on the...

The objective of this study was to evaluate the energy use associated with air conditioning hotel guest rooms under three different control strategies:Baseline: the digital thermostat was manually controlled by the guestOccupancy Controls: DDC thermostat with integrated occupancy sensor and energy...

Data centers are among the most energy-intensive facilities. Air management is not only imperative for energy management but also for thermal management. The goal of air management is to supply as little supply air as possible at as high temperature as possible without adversely affecting the...

The purpose of the project is to verify the performance and efficiency of a 5-ton indirect evaporative hybrid roof top air-conditioning unit developed primarily for the small commercial market...

Project SummaryA significant portion of the energy in data centers is currently dedicated to provide cooling for the server equipment. Data centers must provide continuous air conditioning to address high internal heat loads (heat release from computer servers) and maintain indoor temperatures...

Project SummaryPlastic resin has to be dried to set moisture level prior to feeding into injection molding, blow molding, or other extrusion machines.  The conventional drying technology is to use a twin bed descant dryer for this purpose.  The twin bed is for one bed to be in drying mode...