Solar thermal engineering space heating and hot water systems

Solar Energy ◽  
1982 ◽  
Vol 28 (1) ◽  
pp. 86
Author(s):  
Michele Totaro ◽  
Anna Laura Costa ◽  
Lorenzo Frendo ◽  
Sara Profeti ◽  
Beatrice Casini ◽  
...  

Despite an increase of literature data on Legionella spp. presence in private water systems, epidemiological reports assert a continuing high incidence of Legionnaires’ disease infection in Italy. In this study, we report a survey on Legionella spp. colonization in 58 buildings with solar thermal systems for hot water production (TB). In all buildings, Legionella spp. presence was enumerated in hot and cold water samples. Microbiological potability standards of cold water were also evaluated. Legionella spp. was detected in 40% of the buildings. Moreover, we detected correlations between the count of Legionella spp. and the presence of the optimal temperature for the microorganism growth (less than 40 °C). Our results showed that cold water was free from microbiological hazards, but Legionella spp., was detected when the mean cold water temperature was 19.1 ± 2.2 °C. This may considered close to the suboptimal value for the Legionella growth (more then 20 °C). In conclusion, we observed the presence of a Legionnaires’ disease risk and the need of some strategies aimed to reduce it, such as the application of training programs for all the workers involved in water systems maintenance.


Author(s):  
W. H. Eccleston

This paper covers some of the basic considerations associated with the practice of heating, ventilating and air-conditioning in temperate climates. A diagrammatic representation of heat loss and gain for a room appears to provide a key to more accurate forecasting of fuel consumption for whole buildings. Further, the smaller the thermal capacity of the system and, therefore, the quicker the response rate, the larger is the possible scope for fuel savings. As far as space heating is concerned water systems are classified and there is reference to the more commonly used heat emitters and some of their characteristics. There is some reference to boiler power both for hot-water heating and steam generation. Ventilation is discussed in the context of terminal points; there is also a brief reference to noise attenuation in ducts and to balancing of systems. Air-conditioning is defined and the better known distribution methods are classified. Packaged water chillers are briefly examined and there are some suggestions regarding ‘mixing-units’. In addition there are some comments on cooling towers. In conclusion there is a plea for standardization and in this particular instance reference is made to specifications for mechanical services works.


2014 ◽  
Vol 61 ◽  
pp. 234-237 ◽  
Author(s):  
G. Comodi ◽  
M. Bevilacqua ◽  
F. Caresana ◽  
L. Pelagalli ◽  
P. Venella ◽  
...  

Author(s):  
Jenny Chu ◽  
Cynthia A. Cruickshank ◽  
Wilkie Choi ◽  
Stephen J. Harrison

Heat pumps are commonly used for residential space-heating and cooling. The combination of solar thermal and heat pump systems as a single solar-assisted heat pump (SAHP) system can significantly reduce residential energy consumption in Canada. As a part of Team Ontario’s efforts to develop a high performance house for the 2013 DOE Solar Decathlon Competition, an integrated mechanical system (IMS) consisting of a SAHP was investigated. The system is designed to provide domestic hot water, space-heating, space-cooling and dehumidification. The system included a cold and a hot thermal storage tank and a heat pump to move energy from the low temperature reservoir, to the hot. The solar thermal collectors supplies heat to the cold storage and operate at a higher efficiency due to the heat pump reducing the temperature of the collector working fluid. The combination of the heat pump and solar thermal collectors allows more heat to be harvested at a lower temperature, and then boosted to a suitable temperature for domestic use via the heat pump. The IMS and the building’s energy loads were modeled using the TRNSYS simulation software. A parametric study was conducted to optimize the control, sizing and configuration of the system. This paper provides an overview of the model and summarizes the results of the study. The simulation results suggested that the investigated system can achieve a free energy ratio of about 0.583 for a high performance house designed for the Ottawa climate.


2019 ◽  
Vol 887 ◽  
pp. 650-658
Author(s):  
Christoph Moser ◽  
Gerald Englmair ◽  
Hermann Schranzhofer ◽  
Andreas Heinz

A TRNSYS model of a novel PCM heat storage, utilizing stable supercooling of Sodium Acetate Trihydrate (SAT), is presented. To achieve high solar fractions in heat supply of single family houses, the necessary integration of big water volumes is challenging. To evaluate its functionality, a system model of a solar thermal combisystem for space heating and domestic hot water supply for dynamic system simulation was built. The key component is a PCM volume for long term heat storage. While conventional heat storage concepts with SAT release the latent heat a few degrees below the melting temperature, with the concept of stable supercooling latent heat can be stored for long periods of time at ambient temperature. This allows the design of a partly loss-free storage. Solar fractions were evaluated for simulation runs with two building variations. Annual specific space heating demands of 15 and 30 kWh/(m2a) and a domestic hot water demand of a typical single family house were considered. A sensitivity analysis on solar fractions of domestic heat supply was performed by variation of the collector field and the PCM volume. While the increase of the PCM volume from 4.5 m3 to 9 m3 shows moderate effects in all simulation runs, an increase of the collector area has substantial effects on the share of solar heat on the total energy demand of the building.


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