evaporative cooling

Aim of this work has been to determine the effectiveness of evaporative cooling and ventilation control strategies on a case study to ensure an adequate combination between energy efficiency and high levels of indoor comfort.
The case study has been a kindergarten, situated in the context of the climate continental Mediterranean area (Cerignola, Italy, 41°16'00"N, 15°54'00"E, 120 m asl), oriented on an east/west axis, classrooms south faced, and the services zone to north.

In a case study on outdoor mist cooling, 141 people attending an open campus event were surveyed over 2 hot summer days. Nozzles mounted on an oscillating fan sprayed about 18L/h of mist with average droplet diameter of 25μm. Subjects stood in the misting area where they wished. Time spent in the misting area was recorded. Skin temperature of the forearm and face were taken with IR surface thermometers before entering and after leaving the misted area.

Passive cooling in the built environment is now reaching is phase of maturity.  Passive cooling is achieved by the use of techniques for solar and heat control, heat amortization and heat dissipation. Modulation of heat gain deals with the thermal storage capacity of the building structure, while heat dissipation techniques deal with the potential for disposal of excess heat of the building to an environmental sink of lower temperature, like the ground, water, and ambient air or sky.

This research concentrates on evaporative cooling, a sustainable and alternative way to cool a roof surface by taking advantage of the properties of porous materials. During periods of rain or high humidity nights, water sorbents store moisture in their small pores inside their particles. During a warm sunny day, the latent heat released due to evaporation of moisture, maintains the surface temperature at low level. Lower roof temperatures contribute to smaller heat flow inside the building while reducing the cooling load.

The potential application of Passive and Hybrid Downdraught Cooling to residential buildings is explored using an experimental facility constructed and tested in Seville, Spain. The experiment was devised as a prototype of the downdraught evaporative cooling system for the Nottingham University entry to the 2010 Solar Decathlon Europe competition.

An automotive part manufacturing plant in Southern Italy, which has just recently been modernized and extended, offers an interesting panorama of innovative cost-effective solutions for ventilating, air-conditioning and process cooling.

A novel ventilation system has been installed in buildings constructed for the New Campus of the University of Nottingham. Super-efficient mechanical ventilation has been used as part of an integrated environmental strategy and operates with fan input powers below 0.5 W. l-1.  s-1 of airflow. The complete plant was assembled from innovative low-pressure components and has exceptional performance. A key element of the design is that components of the system are bypassed when not in use. At the heart of the system is a low-velocity, high efficiency thermal wheel.

In buildings with passive downdraught evaporative cooling (PDEC), occupants are subjected to environmental conditions which might be characterised by elevated relative humidities, increased air speeds, and time-varying internal conditions. A new physiological model which describes the human thermophysical system, and the active control exercised on it, has been produced. The model predicts skin and core temperatures, sweat rates, etc. on different parts of a seated, standing or exercising human.

This paper describes part of an EC funded Joule project in which computer simulation has been used to investigate the viability of applying passive downdraught evaporative cooling (PDEC) to non-domestic buildings in hot dry climates. Using analytical techniques, CFO and thermal simulation, the performance-driven anatomy of PDEC buildings has been elucidated and engineering sizing methods have been developed. It is concluded that PDEC should formulate part of an holistic and carefully integrated solution.

In many countries, besides the hot dry climate, the lack of energy resources is one of the brakes to the development: without air conditioning, it is not yet possible to give good conditions of working inside offices; air movements, dust, pollution are not consistent with cleanliness, controlled atmosphere and calm air. Furlhermore, sanitary spaces as hospitals and laboratories, and cultural ones as museums and libraries are interested in passive solutions to cooling in a closed atmosphere, ie: without any air movement, except controlled-filtered ventilation.