thesis(sph).pdf - ethesis

This confirms that a thesis entitled "Thermodynamic, Economic Analysis and Design of Swimming Pool Heating System at NIT Rourkela" has been submitted. The swimming pool at NIT Rourkela currently does not have a heating system to heat the pool water in winter. The focus of this project is on the design of an efficient and economically viable pool heating system.

NIT Rourkela has a large recreational center in the form of swimming pool located in its campus. Students, faculty, and staff enjoy the benefits of the pool, which not only provides a great source of fun and enjoyment, but is also a great way to stay healthy and fit. To extend the benefits of the pool throughout the year, a heating system should be installed in the pool which can provide a comfortable swimming temperature during the winter.

The aim of this project is to design a pool heating system that is both effective and cost effective. Different methods available to heat a pool need to be thoroughly reviewed and their pros and cons well studied in order to have a perfect heating system.

HEAT LOSSES ASSOCIATED WITH THE SWIMMI G POOL

EVAPORATIVE LOSSES: [1],[2]

This loss is related to the temperature difference between the water in the pool and the surrounding air. When water or air velocity is negligible, natural convection prevails instead of forced convection. Evaporation is a factor in increasing natural convection, as it is related to the creation of differences in air density.

There is no noticeable heat loss from convection when the temperature of air and water are equal.

RADIATION HEAT LOSS: [1],[2]

Net radiant heat loss from the surface of the pool to the air = radiation emitted by the pool - (reflected radiation + infrared radiation emitted by the walls that is absorbed by the pool). To use the formulas, the surface emissivity of the water, air and pool must be known.

LOSSES DUE TO CONDUCTION: [1],[2]

LOSSES DUE TO GROUND: [1],[2]

METHODS TO HEAT THE SWIMMI G POOL

The pool water absorbs heat as it passes through heated copper pipes and then returns to the pool. These heat pumps extract heat from the outside air and redirect it into the pool. This warm gas increases the heat and thus heat is exchanged between the warm cooling gas and the relatively cool water in the pool.

These are the typical heaters that use electricity as input to heat the pool water. These are direct type pool heaters and have a heater inside them that heats the pool water. If this heat loss can be limited, a lot of energy can be saved to heat the pool.

These coverings consist of small air pockets that trap the heat collected from the sun. These rings can reduce evaporation, help heat the pool water and help conserve chemicals needed by the water.

Figure 4: schematic diagram of a heat pump. [18]

The developed model was experimentally validated for different structural designs of the tested SSEs. After validation, this design tool can be used to design and virtually prototype new flat panel solar panels. A techno-economic assessment has been done for these systems keeping in mind the Indian market.

Simulation software TRNSYS has been used to perform feasibility studies of a solar-assisted heating system. A thermodynamic as well as an economic analysis has been made for the Aquatic Center at the University of Miami. A transient analysis has been made of an indoor swimming pool connected to a panel of collectors.

To validate the model, calculations were made for an Australian swimming pool under active and passive operation. In this article, the effect of using a pool cover on energy savings has been investigated. The developed method allows the establishment of technical and constructive parameters for a flat plate solar collector.

A series of optical tests were performed on pool coatings to determine the properties of different types of pool coatings. In this paper, a transient analysis of a swimming pool, with and without a pool cover, with and without a heat exchanger, has been made. In this work, different types of domestic water heating systems are compared with each other.

An economic analysis was done for all of these and their total annual costs were compared. We studied two types of models of compound parabolic concentrators - stationary and trailing - and determined their thermal efficiency. An internal pool was used for optimization and various continuous and discrete parameters were optimized.

TABULATION OF TEMPERATURE DURING WINTERS

EVALUATING LOSSES FROM SWIMMING POOL USING THE EXPERIMENTAL DATA

DESIGN PARAMETERS FOR A HEATING SYSTEM BASED ON HEAT PUMPS

DESIGN OF SOLAR PANEL FOR HEATING SYSTEM BASED ON SOLAR WATER HEATING (SWH)

DESIGN PARAMETERS USING GAS HEATERS FOR HEATING SWIMMING POOL WATER

CALCULATION FOR HEAT REQUIREMENT BY POOL FOR A 10 DEGREE RISE IN TEMPERATURE

SAMPLE CALCULATION OF HEAT LOSSES USING EQUATIONS DEVELOPED BY BRAMBLEY [1]

SAMPLE CALCULATION FOR OPERATING COST OF A HEAT PUMP Assumption: heating cycle = 6 hours

SAMPLE CALCULATION FOR OPERATING COST OF A GAS HEATER

DESIGING OF HEATING SYSTEM BASED ON HEAT PUMPS

DESIGNING OF HEATING SYSTEM BASED ON SOLAR ENERGY OR SWH SYSTEM

DESIGNING OF HEATING SYSTEM BASED ON GAS HEATERS

Figure 16: change of water and air temperature in the pool for each day of the month at 9:00 AM.

Evaporative, conductive, convective and radiant heat losses were calculated and percentage of each loss was plotted in a pie chart. To show the % contribution of each loss, pie charts have been made for several days at 12:00 noon time.

Table 6: losses calculation at 12:00 noon

ECO OMIC A ALYSIS OF HEAT PUMP BASED WATER HEATI G SYSTEMS

Each KW rating model has two variants, one with a low COP and the other with a high COP. Monthly running costs have been calculated for each model and the number of units required for each model to raise the pool water temperature by 10 degrees Celsius over a 6 hour heating period has been estimated. Although the operating costs of a model with two different COPs are the same, the cost and heat output will differ.

For the same KW model, a higher COP model provides more heat and is more expensive than a low COP model. The purchase and installation costs of each model are constant and their monthly running costs vary depending on existing electricity tariffs, which vary from place to place and also how electricity is generated.

Table 7 :cost analysis and no. Of unit required for each model

Cost analysis was performed for various rating and efficiency models of natural gas heaters. We see that as the KW rating increases, no units required decrease and the monthly cost also increases.

As we can see from the data, the number of units required in the case of natural gas stoves is too high. From the table, we see that although the monthly operating cost of a single natural gas heater is lower than that of a heat pump for the same power, but as a large number of natural gas heaters are required, the annual operating cost of natural gas heaters skyrockets compared to heat pumps.

Table 9 : cost comparison between heat pumps and natural gas heaters.

DESIG I G OF WATER HEATI G SYSTEM BASED O SOLAR E ERGY

Temperature variation of pool water and air above the pool at different times was recorded for the month of November. Graphs were plotted based on this data that showed the intersection of two temperature curves at least once a day. Based on the temperature data obtained, various losses associated with the pool were calculated and the percentage of each loss in relation to the total loss was shown in the form of pie charts.

Heat pumps are very efficient, but they are very expensive and a threat to the environment. Although they are effective heaters, they are 2-3 times more expensive than heat pumps, and natural gas is a renewable energy source, so its use as a means of heating pools should be avoided. In this way, we use the abundant solar energy and also make the system efficient by incorporating conventional heating.

For the entire winter season, i.e. from October to February, the pool water temperature, air temperature above the pool, humidity and air speed can be recorded. Using this data, mathematical equations and models can be developed for swimming pools located in tropical climates such as Rourkela. Based on the experimental results, the power generated by each panel and the size of each panel can be calculated.

The number of panels required can be calculated and these panels can thus be manufactured for heating swimming pool water. A swimming pool cover can be installed over the pool to reduce losses due to evaporation. Evaluation of Economic and Thermal Performance of Closed Solar Hybrid Air and Water Heating Systems for Indian Climates, Energy Convers, Mgmt Vol pp.

Determination of the technical design parameters of a flat solar collector by numerical calculation taking into account the temperature criterion, Romanian Reports in Physics, Vol pp. Optical Characteristics of Swimming Pool Covers Used for Direct Solar Heating, Solar Energy, Vol 26, 1981, p. Economic analysis and comparison of two solar systems with sanitary water heating systems, Tr.J.