Analysis and Evaluation of Heat Pipe Efficiency to Reduce Low Emission with the Use of Working Agents R134A, R404A and R407C, R410A

This paper presents an analysis of methods to increase the efficiency of heat transfer in heat exchangers. The scope of the research included analysis of efficiency optimization using the example of two tubular heat exchanger structures most often used in industry. The obtained efficiency of heat recovery from the ground of the examined exchangers was over 90%, enabling the reduction of emissions of the heating systems of buildings. The paper presents the results of tests of two types of heat pipes using R134A, R404A, and R407C working agents. The paper also presents the results of experimental tests using the R410A working medium. The results included in the study will also enable the effective use of land as a heat store.

Methodology Applied for Thickness Selection and Stored Heat Evaluation in Non-producer Geothermal Wells in Order to Its Investment Rescue

An assessment methodology of stored heat in rock formation surrounding to wellbore in geothermal systems is shown. Due to geothermal systems generally are nested in volcanic rock, it is characteristic its heterogeneous behavior. Proposed methodology starts since zone selection with possibilities of heat store. This methodology is focused to be applied in geothermal reservoirs with tendency to production decline, due to low permeability and unbalance between exploitation and water recharge. Because the high costs of drilling geothermal wells, methodology shown in this work is proposed to be applied in those with production decline or non-producers, in order to rescue its investment. The objective is to select the thickness with heat, evaluate its storage, design the appropriate instrumentation for its recovery, its energy conversion and rescue its investment done. The different designs for energy recovery using non-conventional methods to those, used habitually are reviewed. Each one of the variables for stored heat calculation was determined using technical tools of reservoir engineering. A parametric analysis about variables sensitivity (porosity and drainage radius) for determining thermal energy and corresponding electric energy of analyzed rock volume is done. Practical application of this methodology was carried out using data of one of wells of Los Humeros Mexican geothermal field.

Trombe Wall Application with Heat Storage Tank

In this study, an investigation was made of the performance of a Trombe wall of classical structure used together with a heat store. Most Trombe walls are able to supply the heating needs of a space to which they are connected without the need for extra heating at times when the sun is shining. However, the heat obtained from the Trombe wall can be in excess of needs at such times, and measures must be taken to provide ventilation to the heated space. It is thought that the heat energy can be used more efficiently and productively by storing the excess heat outside the building and using it inside the building when there is no sunlight. To this purpose, a tank full of water and marble was built as a heat store as an alternative to the general Trombe wall design, and an attempt was made to minimise heat losses by burying it in the ground. It was concluded that in place of a traditional Trombe wall system using a massive wall heat store, a heat store could be constructed in a different position and with different materials. The Trombe wall system which was developed and tested met up to 30% of the energy needed for heating and cooling the building, and reduced the architectural and static disadvantages of Trombe wall systems. As a result of the study, it was seen that where a standard reinforced concrete wall could supply heat to the inside for 7 hours and 12 minutes, the figure for a wall made of paraffin wax was 8 hours and 55 minutes. In the same study, the heat storage thickness of a reinforced concrete wall was calculated as 20 cm, while that of a paraffin wax wall was calculated as 5 cm.

The use of sand deposits in buildings for energy storage

The aim of the research is to prepare data for the design of heat stores with sand filling. In buildings without basement, spaces between foundation walls are filled with material easily compacted, which forms a solid and durable basis for the ground level of the building. As a rule, this material is sand of various grain size, and foundation walls are insulated. In this way, a space filled with a granular material is formed, which, with a properly designed heat exchanger attached, may be used as sensible-heat storage. Such a store makes a good lower level source for heat pumps - source of heat at the time of low temperatures outside, which significantly raises the coefficient of efficiency of the system. Low construction cost of the heat exchanger is an additional argument for the use of the space between the foundation walls for the purpose of building a heat store. This paper presents the results of studies that allow of the appropriate design of the heat exchanger in a heat store with a granular deposit. The deposit temperature changes in time have been studied, dependent on the distance from the source of heat and humidity of the material. Study was carried out for the sands used for filling the space between the foundation walls.

Study on Application of Solar Heating System Integrated Latent Heat Store Heat Exchanger

This paper introduces the design of a solar heating system integrated latent heat store heat exchanger. Aiming at studying the system solar fraction, mathematical models are established for describing solar collector, latent heat store heat exchanger, users’ heating thermal load, and the system in whole. Studies are carried out based on these models. The results show that there are some key influencing factors on solar fraction, including solar irradiance, collector area, collector inclination angle, the difference value between collector inlet fluid temperature and ambient air temperature. Among these, collector inclination angle is the most significant one. If the values between collector inlet fluid temperature and ambient air temperature have big difference, it’ll cause adverse effects. As long as the operation requirements are met, lower collector inlet fluid temperature and suitable ambient air temperature are reasonable conditions for application. The research results provide guide for the system application in engineering.