cooling

The authors have proposed a system for stabilizing air temperature using direct heat exchange between granulated phase change materials (PCM) and air. This paper describes experiments in which air whose temperature is periodically changed to simulate changes of outdoor air temperature is passed through a bed of granulated PCM. These experiments demonstrate that output air temperature is stabilized and remains within the phase change temperature range. Results calculated by a computer simulation program described in a previous paper duplicate the experimental results.

Even in cold climates, offices normally need to be cooled due to the internal heat loads from people, equipment and lighting. Either a chilled ceiling or chilled beams with cooled water as medium or chilled air can be used. In the case with chilled ceiling or chilled beams, a constant air volume system (CAV) is used. In the case of air only, a variable air volume (VAV) system must be used. This paper presents the advantages of the two methods of cooling with respect to energy use, which was calculated from climate data.

This paper presents the configuration and some experimental performance data for an improved, custom designed heat recovery & air conditioning retrofitting system, developed for a hospital located in a Canadian cold-climate environment. The two-stage heat recovery system includes a conventional glycol heat exchanger and a prototype of a reversible air-to-air heat pump between the exhaust and the fresh air streams.

CEN/STAR establishes needs for co-normative and pre-normative research in support to CEN standardization. A workshop took place in CETIAT (France) on 23-24 january 2003, its aim was to provide an overview of the trends of research and future standardization for HVAC appliances and to define the needs for pre-normative or co-normative research and interaction with standardization works.

A low energy office building in Frankfurt (Germany) with water heating/cooling from ceilings was submitted to detailed measurements during two years, in the frame of a demonstration project. Results are given showing thermal comfort and energy consumption data.

Up to now, the use of a single HVAC unit to handle ventilation along with mechanical cooling was the aim of designers : it permitted to curb the cost of a building's mechanical system. In this article the author suggests a new design approach to treat the ventilation air and to manage the latent cooling load for the building. It consists in "splitting" the building's total cooling load with a DOAS. This approach allows each component of the HVAC system to do what it does best.

Maintenance of air-conditioning systems is acknowledged as an important means to run HVAC-systems properly. Although several maintenance programs and standards exist, not many systems are maintained in a proper way. Most standards and programs are not concerned with the indoor environment, they are only concerned with repair and failure-response of system components. Just now, some new guidelines come out in Europe, which contains first definition of cleanliness.

In air-based systems, ducts deliver heat and cool air to conditioned spaces. Taking extra time to properly seal ducts during the installation along with repairing and patching leaks in HVAC duct systems will save cooling, heating and fan energy. With aerosol-sealing technology higher performance ducts in new and existing buildings potentially exist.

This paper is a report on humidity control in schools mainly located in hot and humid climates : according to the US Department of Energy's investigation, most of them, use packaged cooling equipments that are not able to manage space humidity effectively when delivering a high percentage of outdoor air. Those schools don't respect the requirements of the ANSI/ASHRAE standard 62-1999.
By using the dedicated outdoor system (DOAS) approach, ventilation effectiveness and humidity control can be improved and meet the recommendations of the ASHRAE 62-1999 standard.

The article describes the different types of cold beams used to cool rooms from cold water. Passive cold beams mainly exchange through radiation and natural convection ; they include no fresh air introduction. Active cold beams are mainly based on forced convection, hot air from the room being induced by fresh air. Mix systems try to combine radiation and forced convection. Main characteristics and advantages of cold beams as well as system design rules are also briefly given.