José A. Orosa

A new modelling methodology to control HVAC systems

Thermal comfort plays an important role in any working environment, but it is a very vague term and it is also very difficult to represent it on modern computers. Its proper definition could be a condition of the mind which expresses satisfaction with the thermal environment and, therefore, it depends on the individuals physiology and psychology. Several researchers have investigated the relationships between room conditions and thermal comfort. Generally speaking, statistical approaches had been used whereas fuzzy and neural approaches have been recently proposed. In this work it is proposed a new thermal comfort model based on the P.O. Fanger PMV index according to the Institute of the University of Kansas and it has been adapted to a specific indoor ambience with a thermal comfort logger. The results showed that this methodology puts forward an adequate accuracy and suggests temperatures according to the present HVAC standards and those adaptive models show adequate values for thermal neutralities even though they are not suitable for energy saving due to its static value on a daily basis.

New Climatic Indicators for Improving Urban Sprawl: A Case Study of Tehran City

In the modern world, the fine balance and delicate relationship between human society and the environment in which we exist has been affected by the phenomena of urbanisation and urban development. Today, various environmental factors give rise to horizontal dispersion, spread and growth of cities. One of the most important results of this is climatic change which is directly affected by the urban sprawl of every metropolis. The aim of this study is to identify the relationship between the various horizontally distributed components of Tehran city and changes in essential microclimate clusters, by means of the humidex index. Results showed that, when the humidex was calculated for each of the obtained clusters, it was evident that it had increased with time, in parallel with Shannon’s entropy, as a consequence of the average temperature and relative humidity of each cluster. At the same time, results have shown that both temperature and relative humidity of the study area are related with urban sprawl, urbanisation and development, as defined by Shannon’s entropy and, in consequence, with humidex. In consequence, this new concept must be considered in future research works to predict and control urban sprawl and microclimate conditions in cities.

Effect of climate change on outdoor thermal comfort in humid climates

BackgroundGalicia, in northwest Spain, experiences warm summers and winters. However, the higher relative humidity that prevails the whole year through and the location of the summer hot points are related to real weather heat stroke in the hottest season. However, Planet Global Heating was recently analyzed for the climate in Galicia. Climate change was found to be able to trigger effects that involve a new situation with new potential regions of risk. In this paper, 50 weather stations were selected to sample the weather conditions in this humid region, over the last 10 years. From these results, new regions with a potential for heat stroke risk in the next 20 years were identified using the humidex index.ResultsResults reveal that during the last 10 years, the winter season presents more comfortable conditions, whereas the summer season presents the highest humidex value. Further, the higher relative humidity throughout the whole year reveals that the humidex index clearly depends upon the outdoor temperature.ConclusionsGlobal Planet Heating shows a definite effect on the outdoor comfort conditions reaching unbearable degrees in the really hottest zones. Therefore, this effect will clearly influence tourism and risk prevention strategies in these areas.

New procedure for wind farm maintenance

Purpose – Conditions monitoring system (CMS) is a tool for describing the present condition of the components of a system. To achieve this objective, there is a need to develop an efficient fault prediction algorithm. This paper seeks to address this issue.Design/methodology/approach – The paper analyses four real wind farms with control charts of indices derived from UNE EN15341:2008 standard indicators, as the main CMS algorithm to define which index must be considered for improving wind farm maintenance and related costs.Findings – The findings show that climatic conditions are related to maintenance cost indices. Employing the statistical control process of various wind energy converter (WEC) indices proposed by wind farm operators is an adequate procedure to monitor and control wind farm performance. In particular, only the maintenance cost index and the hourly maintenance cost index presented a clear relationship with respect to weather conditions.Practical implications – Climatic conditions must fo...

Software tools for HVAC research

Energy saving methods can be employed to reduce energy consumption in buildings, or improve indoor thermal conditions. An example of those methods is the use of permeable coverings, but there are other important parameters like thermal inertia. To understand and predict these energy saving procedures, one may employ different software resources. In the present paper a review of existing software resources is carried out, and, as a consequence of this review, HAM tools were selected to simulate the indoor environment of school buildings. Results show that parameters like thermal inertia can interfere in the solar heat gains, changing the building time constant. Other parameters, like air changes per hour or the use of permeable coverings, present a clear enhancement of indoor environment conditions.

Wind turbine concentrator design based on moist air phase change

This current article shows a procedure to improve wind turbines for kinetic energy conversion in mechanics using a new concentrating design based on moist air phase change. This concentrator presents special interest in the European Atlantic Coast because its weather is mild with a high relative humidity and its winds represent low values for wind turbines applications. Results show a clear possibility of improvement in energy conversion and wind turbine control system.

Galician climatic change effect on wind power production

Galician climate conditions present the right ambience for wind turbines power generators during winter and spring seasons even though its climate change may affect wind velocity and moist air density by reducing the energy conversion. Planet Global Heating was analyzed for Galician climate showing a rise in the average temperature in each season. In this paper twenty-four wind turbines were analyzed in a typical year to get a model that relates weather to power conversion. Once done that, the effect of the climate change was evaluated in Galician wind farms showing a 10% fall during spring and summer season. Therefore, future researches about new technologies more suitable for that work conditions like low wind turbines must be done.

Realistic Solutions for Wind Power Production with Climate Change

Abstract Nowadays, it can be stated that climate change will alter weather conditions, and that regarding wind power production, values out of wind turbine design conditions will occur. In this article, a wind concentrator and a wind farm were designed and modeled to predict changes in local power production. The results showed the feasibility of low speed wind turbines, which could not be achieved with traditional wind turbines.

Case study of safe working conditions in spanish merchant ships

Case study of safe working conditions in spanish merchant ships Objective This paper aims to show a practical case study of safety assessment concerning possible injuries and fire occurring in the engine room on-board a merchant ship, due to fatigue. Methods The methodology was centred in literature hazard identification, measurements in real ships and heat stress indices definition. Results Some corrections are proposed in order to obtain a safe environment for workers in the engine control room and to prevent fatigue risks at the engine room. This will allow adequate oil leakage detection and, as a consequence, improve fire prevention. Discussion Training is a preventive control option, but this study allows the understanding of new corrective control options like design corrections.

An Experimental Test of Low Speed Wind Turbine Concentrators

Abstract The climate of Iberia (Spain and Portugal) has adequate conditions for wind power generation during the winter and spring seasons, whereas in the summer, the low wind velocity and the moist air density reduce the possibility of energy conversion. To solve this problem, low speed wind turbines employing a wind concentrator were assessed during the last few years. In this article, a wind turbine concentrator was designed, manufactured, and tested under different moist air density and velocity conditions. Results showed that this wind turbine concentrator showed ideal working conditions during the summer time.