Papers by Angel Valerio
Greenhouse structures are widely used to enable sheltered plant growth. However, traditional tran... more Greenhouse structures are widely used to enable sheltered plant growth. However, traditional transparent greenhouse structures are generally only used in moderate climates because the cost of the energy required for heating in cold climates is prohibitively high. This paper describes a new approach to the design trade-off between light transmission and thermal insulation in greenhouse structures. Here, a low power variable insulation system combining sunlight-concentrating structures and low cost thermal insulation is shown to be a potentially practical solution. Experimental devices have achieved thermal insulation values exceeding 3.33 m 2 K/W (compared to 0.42 m 2 K/W for triple layer polycarbonate greenhouses) while also maintaining light transmittance values greater than 70%.
Thesis Chapters by Angel Valerio
Greenhouse structures have demonstrated success enhancing crop yields in farmlands, but the energ... more Greenhouse structures have demonstrated success enhancing crop yields in farmlands, but the energy for thermal control and lighting make them impractical in cold weather locations because traditional greenhouse construction techniques result in a trade-off between light transmission and thermal insulation. The objective of the project described in this dissertation was to conceptualize, design and test a practical solution to the light transmission and thermal insulation trade-off challenge. The system that was developed is a variable light valve system that can be switched between two states – in one state the system acts as a sunlight transparent window and the other state the system acts as a highly thermally insulated ceiling capable of keeping the structure warm in cold weather conditions. Switching between the two states requires only a simple, low-cost rotation mechanism. The possibility of extending the hours of operation for the light valve system by adjusting the angular position of its light valve elements was also explored.
The light valve system when in its highly thermally insulated state, demonstrated a thermal insulation value above 3.33 W/m2K and 70% light transmittance when in its light transmissive state. In order to achieve this thermal insulation value, air mass transfer losses through the light valve structure were reduced by the implementation of low pressure seal. The experimental devices used to test the light valve system demonstrated it can be constructed using inexpensive and readily available materials. The project described in this dissertation has successfully confirmed a practical solution to reduce the energy use for heating in cold climate greenhouses while maintaining appropriate sunlight transmittance through their structure. The light valve system may represent a practical alternative for cold climate greenhouse horticulture.
The main objective of this thesis is the characterization of a horizontal ground heat pump system... more The main objective of this thesis is the characterization of a horizontal ground heat pump system. The characterization consists on (a) the design of a real-time and continuous coefficient of performance (COP) and energy efficiency rate (EER) calculation model, (b) the determination of the heat rejected to the ground (total and per pipe length unit) and (c) the 2D ground temperature profile determination. One instrumentation methodology and five programs were developed in order to meet these objectives as shown in the next figure. A ground source heat pump system has been installed and tested at the Research Group on Sustainable Edification & Low Temperature Geothermic Studies test room (Escamilla’s Field Igloo), Tecnológico de Monterrey, Monterrey campus, Mexico. The models developed for the construction of the programs, the results obtained and the experimental validation of these results are presented and discussed. The performance parameters were compared statistically versus an analytical model that calculates the four thermodynamic states of the system using characteristic data inputs. The heat rejection to the ground and the temperature profile routines were programmed using a horizontal numerical model solved using a simplified finite difference approximation. It was observed that the complete characterization meets the experimental results.
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Papers by Angel Valerio
Thesis Chapters by Angel Valerio
The light valve system when in its highly thermally insulated state, demonstrated a thermal insulation value above 3.33 W/m2K and 70% light transmittance when in its light transmissive state. In order to achieve this thermal insulation value, air mass transfer losses through the light valve structure were reduced by the implementation of low pressure seal. The experimental devices used to test the light valve system demonstrated it can be constructed using inexpensive and readily available materials. The project described in this dissertation has successfully confirmed a practical solution to reduce the energy use for heating in cold climate greenhouses while maintaining appropriate sunlight transmittance through their structure. The light valve system may represent a practical alternative for cold climate greenhouse horticulture.
The light valve system when in its highly thermally insulated state, demonstrated a thermal insulation value above 3.33 W/m2K and 70% light transmittance when in its light transmissive state. In order to achieve this thermal insulation value, air mass transfer losses through the light valve structure were reduced by the implementation of low pressure seal. The experimental devices used to test the light valve system demonstrated it can be constructed using inexpensive and readily available materials. The project described in this dissertation has successfully confirmed a practical solution to reduce the energy use for heating in cold climate greenhouses while maintaining appropriate sunlight transmittance through their structure. The light valve system may represent a practical alternative for cold climate greenhouse horticulture.