Thermal behaviour of closed wet cooling towers for use with chilled ceilings

Facão, Jorge; Oliveira, Armando C.

doi:10.1016/s1359-4311(99)00096-4

Cited by 78 publications

(40 citation statements)

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“…The trend would seem to favour the evaporative cooling of buildings as the lowest approach conditions occur during periods of highest external heat gains. This feature was also recently reported by Facao and Oliveira [12] in the context of the application of closed wet cooling towers to the generation of cooling water for use with chilled ceilings. Facao reports an approximate 8% increase in tower thermal efficiency when the WBT rises from 10 to 20 8C.…”

Section: Experimental Programme Resultssupporting

confidence: 80%

“…A temperature of 18 8C would seem to be the maximum cooling water temperature which can be used with sensible air-water cooling systems, of this type, although this largely depends on the comfort criteria considered acceptable for each project and whether an adaptive approach to comfort conditions could be employed. Two recent research papers state that chilled ceiling panels can operate with a supply water temperature as high as 18-20 8C [14,12].…”

Section: Introductionmentioning

confidence: 99%

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Indirect evaporative cooling potential in air–water systems in temperate climates

Costelloe¹,

Finn

2003

Energy and Buildings

103

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Recent developments have prompted a review of evaporative cooling technology as an effective means of cooling modern deep plan buildings. Prominent among these developments is the success of high temperature sensible cooling systems, particularly, chilled ceilings, which require a supply of cooling water at 14-18 8C. Crucial to the success of evaporative cooling technology, as a significant means of cooling in modern applications, is the ability to generate cooling water, in an indirect circuit, at a temperature which closely approaches the ambient adiabatic saturation temperature (AST) or wet bulb temperature (WBT). Recent experimental research has demonstrated that it is technically viable to generate such cooling water at a temperature of 3 K above the ambient AST.While the frequency of ambient AST occurrence can be obtained from meteorological sources, there is little in-depth analysis of the potential for this form of cooling water generation, based on the approach temperatures which have now been shown to be viable. The decision to use an evaporative cooling system depends largely on an assessment, in-depth, of net energy saved against capital expended. Such an assessment requires detailed data on the availability of cooling water, generated by evaporation, for each location. This paper quantifies evaporative cooling availability in-depth for a northern and southern European city, Dublin and Milan and suggests a method of analysing such data for any world wide location, for which suitable meteorological records are available. The paper, incorporates recent experimental research findings and bases the availability analysis on meteorological test reference weather year data.The results of this research confirm a major potential for the generation of cooling water by evaporative means, which can be used to provide effective cooling of deep plan buildings by means of contemporary water based sensible cooling systems, such as fan coil systems, radiant chilled ceiling panels and ceiling cooling convectors (chilled beams). While the technique offers most potential in locations with a northern European temperate climate, it has significant potential to contribute to cooling in some southern European cities, during the nonsummer months and also at other times, particularly where load shaving techniques are incorporated. #

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Section: Experimental Programme Resultssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Indirect evaporative cooling potential in air–water systems in temperate climates

Costelloe¹,

Finn

2003

Energy and Buildings

103

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“…The thermal performance of closed towers has been the subject of a number of recent research projects undertaken by European Commission supported consortia, from which there are numerous associated publications [5][6][7][8][9][10][11]. Facao and Oliveira describe the development of a prototype closed cooling tower, specially adapted for use with chilled ceilings [5].…”

Section: Introductionmentioning

confidence: 99%

“…Facao and Oliveira describe the development of a prototype closed cooling tower, specially adapted for use with chilled ceilings [5]. The tower has a design cooling capacity of 10 kW, for an inlet water temperature of 21°C and an air wet-bulb temperature of 16°C.…”

Section: Introductionmentioning

confidence: 99%

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Heat transfer correlations for low approach evaporative cooling systems in buildings

Costelloe¹,

Finn

2009

Applied Thermal Engineering

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The experimental performance of an open industrial scale cooling tower, utilising small approach temperature differences (1-3 K), for rejection of heat at the low water temperatures (11-20°C) typical of chilled ceilings and other sensible air-water heat dissipation systems in buildings, is examined. The study was carried out under temperate maritime climatic conditions (3-18°C wet-bulb temperature range). Initially a theoretical analysis of the process at typical conditions for this climate was conducted, which indicated that a water to air (L/ G) mass flow rate ratio of less than 1.0 was required for effective operation. Consequently for these low L/G ratios, the thermal performance of the experimental tower was measured and correlated. A new correlation is proposed which shows a significant increase in the NTU level achieved, for the required L/G ratios (0.3-0.9). As the cooling tower in this application is predominantly a mass transfer device under summer conditions, the evaluation of the total volumetric heat and mass transfer coefficient (kg a s À1 m À3 ) is of particular relevance and is also determined.

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Thermodynamic study of wet cooling tower performance

Papaefthimiou

Zannis

Rogdakis

2006

Int. J. Energy Res.

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SUMMARYAn analytical model was developed to describe thermodynamically the water evaporation process inside a counter-flow wet cooling tower, where the air stream is in direct contact with the falling water, based on the implementation of the energy and mass balance between air and water stream describing thus, the rate of change of air temperature, humidity ratio, water temperature and evaporated water mass along tower height. The reliability of model predictions was ensured by comparisons made with pertinent experimental data, which were obtained from the literature. The paper elaborated the effect of atmospheric conditions, water mass flow rate and water inlet temperature on the variation of the thermodynamic properties of moist air inside the cooling tower and on its thermal performance characteristics. The analysis of the theoretical results revealed that the thermal performance of the cooling tower is sensitive to the degree of saturation of inlet air. Hence, the cooling capacity of the cooling tower increases with decreasing inlet air wet bulb temperature whereas the overall water temperature fall is curtailed with increasing water to air mass ratio. The change of inlet water temperature does not affect seriously the thermal behaviour of the cooling tower.

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Thermal behaviour of closed wet cooling towers for use with chilled ceilings

Cited by 78 publications

References 1 publication

Indirect evaporative cooling potential in air–water systems in temperate climates

Indirect evaporative cooling potential in air–water systems in temperate climates

Heat transfer correlations for low approach evaporative cooling systems in buildings

Thermodynamic study of wet cooling tower performance

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