The diploma thesis is consisting of three parts. The first part is a theoretical overview. It discusses the basic types of refrigeration systems and addresses used by air conditioners. The theoretical part contains describes the basic terms of the proposed refrigeration system, air filtration technology. In the second part of the project design air conditioning systems for offices three-story office building. Following heat balance the budget, the air conditioning system. Numerical solution is completed drawings and bill of material. The third part is experimental. Objective measurement is to determine the heat loss of the pipe without insulation, with normal insulation, new insulation and determine the applicability of a new type of insulation.

Thesis: Mech. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1977 / Includes bibliographical references. / Mech. E. / Mech. E. Massachusetts Institute of Technology, Department of Mechanical Engineering

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The refrigeration and air conditioning systems by adsorption with solar energy are a very interesting option to replace the conventional compression systems because they save energy, are noiseless and use non-aggressive ozone layer refrigerants; however, there are scarcities of studies at this topic. The acquisition of knowledge and positioning in research on this topic by new research groups could be facilitated by knowing the context, trends, and collaborations that emerge in the subject. A map of collaborative co-authors between the greatest authors on the subject was drawn up, the same one that is done using Gephi software. From the analysis of these maps, the centrality degree and collaboration between the authors were determined. / Revisión por pares

A finite difference model simulating a liquid desiccant dehumidification tower with lithium chloride as the desiccant solution has been developed. The model determines the packing height needed for a condensation rate. Comparisons with experimental data illustrates that the model produces valid results. Air and desiccant solution temperatures within the dehumidification tower show that a temperature increase is experienced for both the air and desiccant solution from their respective entrances and exits from the tower. Increasing the air mass velocity or the amount of moisture removed from the air supply causes an increase in packing height. Increasing the desiccant mass velocity decreases the packing height.

The heating and air-conditioning energy demand of skyscrapers with atria between buildings is explored. Radiation, conduction, convection, and ventilation were evaluated to determine annual heating and cooling energy demands for a 100-building city located in Provo, Utah. Spreadsheets models were developed and calibrated with a computational fluid dynamics model. Three spreadsheet model cases were examined: a baseline no-atrium case, a conditioned atrium case, and an unconditioned atrium case. The energy demands and atrium temperatures were compared between the different cases. The research concludes that atria can be used between buildings to reduce the heating and cooling energy demands. The exposed surface area of the city was reduced by 73.7%. This resulted in a 49.7% reduction in heating and cooling energy consumption for the unconditioned atrium case and a 16.0% reduction in energy consumption for the conditioned atrium case.

No description available.

Researchers and practitioners have found that the type of mechanical system utilized to thermally condition a space impacts the noise level for occupants. Indeed, in schools, air conditioning systems are by far the largest contributors to room noise (Bradley, 2002; Nelson et al., 2005; Siebein et al., 2000). Studies have also demonstrated the impact of noise on youth\'s cognitive performance. The problem is worsened in non-native speakers and children with hearing loss (which can be temporary due to colds and allergies or permanent). No studies yet have bridged those two widely-supported findings: if the type of mechanical system impacts (and often dictates) the noise level in the room, and if the noise level in the room impacts the performance of the student, might there be a correlation between mechanical system type and student achievement? An examination of 73 elementary schools in a single Orlando, Florida school district suggests that, for schools populated with students of similar socio-economic background, schools cooling with the noisiest types of mechanical system, with both a compressor and fan exposed to the room, underperformed on standardized student achievement tests relative to those with quieter types of systems. Also, schools with the highest percentages of low socio-economic level children are more likely to get the noisiest type of cooling system. Mechanical system data was gathered through an online survey answered by facility maintenance managers and school percentage student achievement scores on the Florida Comprehensive Assessment Test (FCAT) were obtained from public online data for years 2003 to 2010 for third grade only. This is the earliest students are tested by the FCATs and studies show a larger impact of noise at an early age. This study examined as well the extent to which teachers believe noise from mechanical systems has an effect on student learning and under what conditions. Results from an online survey sent to third grade teachers in the same schools show that teachers generally judge noise levels in their classroom to be sufficiently quiet and do not consider noise to be a problem that needs addressing. However, in open-ended questions teachers demonstrated an understanding of the effects of noise in children\'s concentration and classroom speech communication. / Ph. D.

Presently, auto manufacturers do not have do not have efficient or accurate methods to determine the amount of refrigerant (R-134a) in an air conditioning system of an automobile. In the research presented, vibration analysis is examined as a possible method to determine this R-134a amount. Initial laboratory tests were completed and experimental modal analysis methods were investigated. This approach is based on the hypothesis that the natural frequency of the accumulator bottle is a function of the mass of refrigerant in the system. Applying this theory to a working automotive air conditioning bench test rig involved using the roving hammer method—forcing the structure with an impact hammer at many different points and measuring the resulting acceleration at one point on the structure. The measurements focused on finding the natural frequency at the accumulator bottle of the air condition system with running and non-running compressor scenarios. The experimental frequency response function (FRF) results indicate distinct trends in the change of measured cylindrical natural frequencies as a function of refrigerant level. Using the proposed modal analysis method, the R-134a measurement accuracy is estimated at ±3 oz of refrigerant in the running laboratory system and an accuracy of ±1 oz in the non-running laboratory system. / Master of Science

published_or_final_version / Business Administration / Master / Master of Business Administration

This thesis details a study of strategies used to limit the flow generated noise encountered in the outlet diffusers of high velocity heating, ventilation and air conditioning (HVAC) duct systems. The underlying noise rating criterion is drawn from the specifications covering ocean going aluminium fast ferries. Although directed primarily towards the fast ferry industry the results presented herein are applicable to other niche high velocity HVAC applications. Experimental tests have been conducted to prove the viability of a high velocity HVAC duct system in meeting airflow requirements whilst maintaining acceptable passenger cabin noise levels. A 50 mm diameter circular jet of air was expanded using a primary conical diffuser with a variety of secondary outlet configurations. Noise measurements were taken across a velocity range of 15 to 60 m/s. An optimum outlet design has been experimentally identified by varying the diffuser angle, outlet duct length and the termination grill. A 4 to 5 fold reduction in required duct area was achieved with the use of a distribution velocity of 20 to 30 ms-1, without exceeding the prescribed passenger cabin noise criteria. The geometric configuration of the diffuser outlet assembly was found to have a pronounced effect on the noise spectrum radiating from the duct outlet. The development of a numerical model capable of predicting the flow induced noise generated by airflow exiting a ventilation duct is also documented. The model employs a Large Eddy Simulation (LES) CFD model to calculate the turbulent flow field through the duct diffuser section and outlet. The flow-generated noise is then calculated using a far field acoustic postprocessor based on the Ffowcs-Williams and Hawkings integral based formulation of Lighthill???s acoustic analogy. Time varying flow field variables are used to calculate the fluctuating noise sources located at the duct outlet and the resulting far field sound pressure levels. This result is then used to calculate the corresponding far field sound intensity and sound power levels. The numerical acoustic model has been verified and validated against the measured experimental results for multiple outlet diffuser configurations.